Polarization luminaire and projection display

ABSTRACT

A polarization luminaire is disclosed having a light source that emits light having random polarization directions, a first lens plate and a second lens plate. The first lens plate has a plurality of condenser lenses, the condenser lenses being decentered lenses. The second lens plate is a composite layered element having a condenser lens array, a polarization beam splitting prism array, and a half-wave plate placed on an exit side of the polarization beam splitting prism array. The polarization beam splitting prism array splits each light emitted from both the plurality of condenser lenses and the condenser lens array into a p-polarized light and an s-polarized light. The polarization beam splitting prism array includes a plurality of polarizing beam splitters and a plurality of reflecting mirrors alternately arranged.

This is a Continuation of application Ser. No. 10/098,349, filed Mar.18, 2002 now abandoned, which is a Continuation of application Ser. No.09/690,462, filed Oct. 18, 2000 (now U.S. Pat. No. 6,411,438), which inturn is a Continuation of Ser. No. 08/619,663, filed Feb. 6, 1997 (nowU.S. Pat. No. 6,147,802). The entire disclosure of the priorapplications are hereby incorporated by reference herein in theirentirety. Additionally, application Ser. No. 08/619,663, filed Feb. 6,1997 (now U.S. Pat. 6,147,802) is a 371 of PCT/JP95/01448, filed Jul.21, 1995.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a polarization luminaire for uniformlyilluminating a rectangular illumination area or the like with polarizedlight waves in which the polarization direction thereof is made to beuniform. Further, the present invention relates to a projection displayfor modulating polarized light, which has been emitted from thispolarization luminaire, by means of a light valve and for enlarging animage and displaying the image on a screen.

2. Description of Related Art

Hitherto, a system of the optical integrator using two lens plates hasbeen known as an optical system for uniformly illuminating a rectangularillumination area of a liquid crystal light valve or the like. Thesystem of the optical integrator is disclosed in, for example, JapanesePatent Public Disclosure No. 3-11806/1991 Official Gazette and hasalready been put to practical use.

SUMMARY OF THE INVENTION

Ordinary projection displays, which use liquid crystal light valves ofthe type adapted to modulate polarized light, can utilize only singlekind of polarized light. It is, therefore, important for obtaining alight projected image to enhance the utilization efficiency of light.

An object of the present invention is to propose a luminaire suitablefor using in a projection display or the like, which uses a liquidcrystal light valve of the type adapted to modulate polarized light, asan illuminating system.

More particularly, the object of the present invention is to propose apolarization luminaire that is provided with a system of the opticalintegrator and a polarization conversion system and can efficientlyutilize polarized light and further can achieve uniform illumination.Furthermore, another object of the present invention is to propose aprojection display provided with this newly proposed polarizationluminaire.

A polarization luminaire of the present invention has: a light sourcefor emitting polarized lights whose polarization directions are random;and a system of the optical integrator that is provided with a firstlens plate consisting of a plurality of lenses and with a second lensplate consisting of a plurality of lenses. The polarized light radiatedfrom the light source is projected on the entrance plane of each of thelenses of the second lens plate through the first lens plate in such amanner as to form a secondary light source image thereon. Further, anobject is radiated with light emitted from the second lens plate. Thispolarization luminaire of the present invention further has: polarizedlight splitting means for splitting a light emitted from the lightsource into two kinds of polarized lights whose polarization directionsare perpendicular to each other and whose traveling directions are apartfrom each other by an angle of less than 90 degrees; and polarizationconversion means for causing the two kinds of polarized lights to havethe same polarization direction. Moreover, this polarization luminaireof the present invention employs a configuration in which the polarizedlight splitting means is placed on one of an entrance side and an exitside of the first lens plate of the system of the optical integrator.

Here, note that in the case where a region illuminated with polarizedlight emitted from the system of the optical integrator is oblong in thesame manner as a rectangle or the like, it is preferable that asplitting direction, in which two lights split by the polarized lightsplitting means are separated from each other, is the direction of thelength of the region.

Further, it is desirable that the shape of each of the lenses composingthe second lens plate of the system of the optical integrator is similarto that of each of the lenses composing the first lens plate.

An element having a structure (namely, a liquid crystal structure), inwhich a liquid crystal layer is sandwiched between a prism substrate anda glass substrate and an interface between the liquid crystal layer andthe prism substrate is formed as a multi-stage surface inclined at anangle of less than 90 degrees to the optical axis of the means, may beemployed as the polarized light splitting means.

A prism beam splitter, which is provided with a polarized lightsplitting film constituted by a dielectric multi-layer film and isadapted to split a polarized light emitted from the light source, whosepolarization direction is random, into two kinds of polarized lights,whose polarization directions are perpendicular to each other, and isfurther adapted to emit the two kinds of polarized lights respectivelyin directions forming a deviation angle of less than 90 degrees, may beemployed, instead of this element using a liquid crystal, as thepolarized light splitting means.

The following configurations can be employed as that of the prism beamsplitter.

(1) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a flat quadrangular prism and atriangular prism whose inclined surface portion is joined to one ofopposed side surface portions of the quadrangular prism. In a jointportion between the quadrangular prism and the triangular prism, thepolarized light splitting film is formed. A reflection film forreflecting single kind of polarized lights, which is transmitted by thepolarized light splitting film, in a predetermined direction is formedon the other of the opposed side surface portions of the quadrangularprism.

As the aforementioned triangular prism, a triangular prism containingliquid can be employed.

(2) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a first flat quadrangular prismand a second flat quadrangular prism whose side surface portion isjoined to one of opposed side surface portions of the first quadrangularprism. In a joint portion between the first and second quadrangularprisms, the polarized light splitting film is formed. A reflection filmfor reflecting single kind of polarized lights, which is transmitted bythe polarized light splitting film, in a predetermined direction isformed on the other of the opposed side surface portions of the firstquadrangular prism.

(3) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a flat quadrangular prism and aplurality of triangular prisms whose inclined surface portions arejoined to one of opposed side surface portions of the quadrangularprism. In a joint portion between the quadrangular prism and thetriangular prisms, the polarized light splitting film is formed. Areflection film for reflecting single kind of polarized lights, which istransmitted by the polarized light splitting film, in a predetermineddirection is formed on the other of the opposed side surface portions ofthe quadrangular prism.

As the triangular prism described hereinabove, a triangular prismcontaining liquid can be employed.

(4) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a first triangular prism, on theinclined surface of which the polarized light splitting film is formed,and a second triangular prism, on the inclined surface of which areflection film for reflecting single kind of polarized lights, which istransmitted by the polarized light splitting film, in a predetermineddirection is formed. While the first and second triangular prisms are ina state in which the space therebetween is filled with liquid, the firstand second triangular prisms are formed in such a manner as to beintegral with each other.

(5) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a plurality ofquadrangular-prism-like prism composite elements, each of which has: aflat quadrangular prism; a first triangular prism whose inclined surfaceportion is joined to one of opposed side surface portions of thequadrangular prism; and a second triangular prism whose inclined surfaceportion is joined to the other of the opposed side surface portions ofthe quadrangular prism. In each of the prism composite elements, thepolarized light splitting film is formed in the joint portion betweenthe quadrangular prism and the first triangular prism, and a reflectionfilm is formed in the joint portion between the quadrangular prism andthe second triangular prism. The prism composite elements are aligned ina line in a direction perpendicular to the optical axis of the system ofthe optical integrator in such a way that the polarized light splittingfilms become parallel. The reflection film reflects to output therandomly-polarized light having been emitted from the light sourceportion to the next prism on one side, and reflects the polarized lightwhich is transmitted by the polarized light splitting film formed in thesame prism composite element in a predetermined direction on the otherside.

In this case, the prism composite elements are set in such a manner thatthe polarized light splitting films are inclined at about 45 degrees tothe optical axis of the system of the optical integrator.

(6) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a plurality ofquadrangular-prism-like prism composite elements, in each of which thepolarized light splitting film is formed. The prism composite elementsare aligned in a line in a direction perpendicular to the optical axisof the system of the optical integrator in such a way that the polarizedlight splitting films extends nearly in the same direction.

(7) A prism beam splitter having the following configuration can beemployed. This prism beam splitter has a plurality ofquadrangular-prism-like prism composite elements, in each of which thepolarized light splitting film is formed. The prism composite elementsare aligned in a line in a direction perpendicular to the optical axisof the system of the optical integrator. Moreover, on both sides of theoptical axis of the system of the optical integrator, the polarizedlight splitting films extend nearly in the opposite directions.

Incidentally, in the case that the prism beam splitter has a prismcomposite element as described above, the width measurement of thisprism composite element can be set as follows. If each of the lensescomposing the first lens plate of the system of the optical integratoris a rectangular lens, the width measurement of the prism compositeelement can be set at (1/n) of the width measurement of this rectangularlens (incidentally, n is an integer which is equal to or larger than 1).

Further, a deviation prism can be disposed between the polarized lightsplitting means and the system of the optical integrator. Alternatively,a deviation prism can be placed between the light source and thepolarized light splitting means. In this case, the deviation prism canbe formed in such a way as to be integral with an entrance side of thepolarized light splitting means. Further, the deviation prism, thepolarized light splitting means and the first lens plate of the systemof the optical integrator may be formed as an element having asingle-piece construction.

Next, in the case of employing a prism beam splitter as the polarizedlight splitting means, the prism beam splitter may be disposed on theoptical path between the first lens plate and the second lens plate,instead of being placed nearer to the light source side than the firstlens plate of the system of the optical integrator. In this case, aprism beam splitter having the following configuration has only to beemployed. Namely, this prism beam splitter has a flat quadrangular prismand a rectangular prism whose inclined surface portion is joined to oneof opposed side surface portions of the quadrangular prism. In a jointportion between the quadrangular prism and the rectangular prism, thepolarized light splitting film is formed. A reflection film forreflecting single kind of polarized lights, which is transmitted by thepolarized light splitting film, in a predetermined direction is formedon the other of the opposed side surface portions of the quadrangularprism. The two orthogonally intersecting surfaces of the rectangularprism are used as a surface of incidence and an exit surface. Polarizedlight is incident on the surface of incidence thereof and is then splitby the polarized light splitting film into two kinds of polarized lightsthat are subsequently reflected by the reflection film and are finallyoutputted from the exit surface thereof in such a manner as to beseparated and outputted therefrom, respectively, at angles which arenearly symmetric with the optical axis.

In this case, after the first lens plate of the system of the opticalintegrator is disposed on the surface of incidence of the rectangularprism in a state, in which the first lens is joined thereto and further,the deviation prism is disposed at a position, which is nearer to thelight source side than the position of the first lens, light emittedfrom the light source has only to be incident on the first lens plate ata certain angle of incidence which is not a right angle. Needless tosay, the deviation prism may be disposed between the first lens plateand the surface of incidence of the rectangular prism. Alternatively,the deviation prism may be disposed between the exit surface of theprism beam splitter and the second lens plate.

Next, an optical system using first and second condensing mirror plates,each of which consists of mirrors, instead of the first lens plate maybe employed as the system of the optical integrator. Namely, thepolarization illumination device employing such an optical system has: alight source; a polarized light splitting means that has a structure, inwhich a polarized light splitting film constituted by a dielectricmulti-layer film is sandwiched between two rectangular prisms, and isoperative to split an output light of the light source into p-polarizedlight and s-polarized light, whose polarization directions areorthogonal to each other, by means of this polarized light splittingfilm; a first condensing mirror plate that comprises a plurality ofcondensing mirrors, each of which has a rectangular appearance, and isoperative to condense the p-polarized lights emitted from the polarizedlight splitting means and to form a plurality of secondary light sourceimages represented by the p-polarized lights; a second condensing mirrorplate that has nearly the same size and shape as of the first condensingmirror plate and is operative to condense the s-polarized lights emittedfrom the polarized light splitting means and to form a plurality ofsecondary light source images, which are represented by the s-polarizedlights, at positions slightly different from positions where theplurality of secondary light source images represented by thep-polarized lights are formed; first and second quarter-wave plates thatare disposed between the first condensing mirror plate and the polarizedlight splitting means and between the second condensing mirror plate andthe polarized light splitting means; and a light condenser lens plate,which comprises lenses of the same number as of the condensing mirrorscomposing the first or second condensing mirror plate, and a half-waveplate that are placed in the vicinity of the positions, at which theplurality of secondary light source images represented by thep-polarized lights are formed, and the positions at which the pluralityof secondary light source images represented by the s-polarized lightsare formed.

Here, note that a deviation prism can be formed between the light sourceand the polarized light splitting means.

Further, deviation prisms can be disposed between the polarized lightsplitting means and the first condensing mirror plate and between thepolarized light splitting means and the second condensing mirror plate,respectively.

In the case of using a deviation prism, the deviation prism may beformed in such a manner as to be integral with the polarized lightsplitting means. Further, the deviation prism may be formed in such away as to be integral with the first condensing mirror plate.Alternatively, the deviation prism may be formed in such a way as to beintegral with the second condensing mirror plate.

The polarized light splitting means can be constituted by a flatpolarized light splitting plate.

Further, a liquid-filled prism may be used as the rectangular prismcomposing the polarized light splitting means.

Moreover, in the case that a region illuminated with polarized lightemitted from the system of the optical integrator is oblong in the samemanner as a rectangle or the like, it is preferable that a separatingdirection, in which two kinds of secondary light source images formed bythe two condensing mirror plates are separated from each other, is madeto coincide with the direction of the length of the region.

Furthermore, it is desirable that the shape of each of the lensescomposing the condenser lens plate is similar to that of each of thecondensing mirrors composing the first and second lens plates.

Next, in the case that a prism beam splitter is employed as thepolarized light splitting means, a configuration, in which the prismbeam splitter may be placed within the second lens plate, may beemployed, instead of the configurations, in which the prism beamsplitter is disposed at a position nearer to the light source than thefirst lens of the system of the optical integrator as above described,and in which the prism beam splitter is disposed on the optical pathbetween the first lens plate and the second lens plate as stated above.

The polarization luminaire of the present invention having the formerconfiguration instead of the latter configurations comprises: a lightsource for emitting polarized lights, whose polarization directions arerandom; a first lens plate that comprises a plurality of condenserlenses, each of which has a rectangular appearance, and is operative tocondense polarized lights emitted from the light source and to form aplurality of secondary light source images represented by the polarizedlights; a second lens plate that is placed in the vicinity of aposition, at which the plurality of secondary light source images areformed, and has a condenser lens array, a polarized light splittingprism array, a half-wave plate and an exit side lens; the condenser lensarray comprises condenser lenses of the same number as of the condenserlenses composing the first lens plate; the polarized light splittingprism array being operative to split a polarized light, whosepolarization direction is random, into a p-polarized light and ans-polarized light and comprises a plurality of polarizing beam splittersand a plurality of reflecting mirrors; the half-wave plate being placedon the side of the exit surface of the polarized light splitting prismarray; and the exit side lens being disposed on the side of the exitsurface of the half-wave plate.

In this case, it is similarly desirable that the shape of each of thecondenser lenses composing the second lens plate is similar to that ofeach of the condenser lenses composing the first lens plate.

Further, a deviation prism can be placed between the light source andthe first lens plate. In this case, the deviation prism can be formed insuch a way as to be integral with the first lens plate.

Moreover, lenses of a decentered system may be used as the condenserlenses composing the first lens plate. Similarly, decentered lenses maybe used as the condenser lenses composing the condenser lens array ofthe second lens plate.

Furthermore, it is preferable that the lateral width of each of thecondenser lenses composing the condenser lens array of the second lensplate is made to be equal to that of the polarizing beam splitter.

Incidentally, the quarter-wave and half-wave plates used in each of theaforementioned configurations can be made of TN (twisted nematic) liquidcrystals.

On the other hand, the present invention relates to a projection displayprovided with a polarization luminaire having each of the aforesaidconfigurations. Namely, a projection display that comprises: aluminaire; a modulation means having a liquid crystal light valve whichis operative to modulate polarized light included in luminous fluxradiated from this luminaire and to cause the light to contain imageinformation; and a projection optical system for throwing the modulatedluminous flux onto a screen and for displaying an image thereon, whereinthe luminaire has each of the aforesaid configurations.

Here, note that projection displays are roughly classified into devicesof a type (particularly, referred to as a single-plate type), each ofwhich uses a single liquid crystal light valve, and devices of anothertype, each of which uses a plurality of liquid crystal light valves andthat in the case of attaching importance to the brightness and thedisplay quality of an image, the projection display of the latter typeusing a plurality of liquid crystal light valves is usually used. Theprojection display using a plurality of liquid crystal light valves isrequired to split luminous flux according to the number of the liquidcrystal and thus needs a mechanism therefor.

Therefore, an ordinary projection display has: a color light splittingmeans for splitting luminous flux, which is radiated from the luminaire,into at least two luminous fluxes; and light synthesis means forsynthesizing a synthetic luminous flux from the modulated luminous fluxafter modulated by the modulation means, wherein the synthetic luminousflux obtained by the color synthesis means is applied to a screenthrough the projection optical system and a color image is displayedthereon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A)–(E) are diagrams for illustrating an optical system of apolarization luminaire embodying the present invention, namely,Embodiment 1 of the present invention; FIG. 1(A) is a schematic diagramfor schematically illustrating the configuration thereof; FIG. 1(B) is aperspective view of a first lens plate thereof; FIG. 1(C) is a schematicdiagram for schematically illustrating the configuration of a polarizedlight splitting unit thereof; FIG. 1(D) is a diagram for illustrating asecondary light source image formed on a second lens plate thereof; andFIG. 1(E) is a diagram for illustrating the configuration of a half-waveplate thereof;

FIG. 2 is a schematic diagram for schematically illustrating theconfiguration of an optical system of an example of a projection displayinto which the polarization luminaire illustrated in FIGS. 1(A)–(E) isincorporated;

FIGS. 3(A)–(B) are diagrams for illustrating the configuration ofanother example of a projection display into which the polarizationluminaire illustrated in FIGS. 1(A)–(E) is incorporated; FIG. 3(A) is aschematic diagram for schematically illustrating the configuration of anoptical system thereof; and FIG. 3(B) is a diagram for illustrating theconfiguration of a color filter thereof;

FIGS. 4(A)–(C) are diagrams for illustrating another polarizationluminaire embodying the present invention, namely, Embodiment 2 of thepresent invention; FIG. 4(A) is a schematic diagram for schematicallyillustrating the configuration of an optical system thereof; FIG. 4(B)is a diagram for illustrating the configuration of a polarized lightsplitting portion thereof; and FIG. 4(C) is a diagram for illustrating asecondary light source image formed on a second lens plate thereof;

FIG. 5 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 3 of the present invention;

FIG. 6 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 4 of the present invention;

FIG. 7 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 5 of the present invention;

FIG. 8 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 6 of the present invention;

FIG. 9 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 7 of the present invention;

FIG. 10 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 8 of the present invention;

FIG. 11 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 9 of the present invention;

FIGS. 12(A)–(B) are diagrams for illustrating another polarizationluminaire embodying the present invention, namely, Embodiment 10 of thepresent invention;

FIG. 12(A) is a schematic diagram for schematically illustrating theconfiguration of an optical system thereof; and FIG. 12(B) is a diagramfor illustrating the configuration of a polarized light splittingportion thereof;

FIG. 13 is a schematic diagram for schematically illustrating an opticalsystem of an example of the modification of a polarization luminaireembodying the present invention, namely, the modification of Embodiment10 of the present invention;

FIG. 14 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 11 of the present invention;

FIG. 15 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 12 of the present invention;

FIG. 16 is a schematic diagram for schematically illustrating an opticalsystem of an example of a projection display provided with thepolarization luminaire illustrated in FIGS. 12(A)–(B);

FIG. 17 is a schematic diagram for schematically illustrating an opticalsystem of an example of a projection display of the polarizationluminaire illustrated in FIGS. 4(A)–(C);

FIGS. 18(A)–(D) are schematic diagrams for schematically illustrating anoptical system of a polarization luminaire embodying the presentinvention, namely, Embodiment 13 of the present invention;

FIGS. 19(A)–(D) are schematic diagrams for schematically illustrating apolarization luminaire embodying the present invention, namely,Embodiment 14 of the present invention; FIG. 19(A) is a schematicdiagram for schematically illustrating the configuration of an opticalsystem thereof; FIG. 19(B) is a perspective view of a condensing mirrorplate thereof; FIG. 19(C) is a diagram for illustrating a polarizationoperation thereof; and FIG. 19(D) is a diagram for illustrating asecondary light source image formed on the condensing mirror platethereof;

FIG. 20 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 15 of the present invention;

FIGS. 21 (A)–(13) are schematic diagrams for schematically illustratinga polarization luminaire embodying the present invention, namely,Embodiment 16 of the present invention; FIG. 21(A) is a schematicdiagram for schematically illustrating the configuration of an opticalsystem thereof; and FIG. 21(B) is a perspective view of a condensingmirror plate thereof;

FIG. 22 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 17 of the present invention;

FIG. 23 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 18 of the present invention;

FIG. 24 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 19 of the present invention;

FIG. 25 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 20 of the present invention;

FIG. 26 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 21 of the present invention;

FIG. 27 is a schematic diagram for schematically illustrating an opticalsystem of an example of a projection display provided with thepolarization luminaire illustrated in FIGS. 19(A)–(D);

FIG. 28 is a schematic diagram for schematically illustrating an opticalsystem of another example of a projection display of the polarizationluminaire illustrated in FIGS. 19(A)–(D);

FIGS. 29(A)–(B) are diagrams for illustrating another polarizationluminaire embodying the present invention, namely, Embodiment 22 of thepresent invention; FIG. 29(A) is a schematic diagram for schematicallyillustrating the configuration of an optical system thereof; and FIG.29(B) is a diagram for illustrating the configuration of a polarizedlight splitting portion thereof;

FIG. 30 is a schematic diagram for schematically illustrating an opticalsystem of an example of the modification of a polarization luminaireembodying the present invention, namely, the modification of Embodiment23 of the present invention;

FIG. 31 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 24 of the present invention;

FIG. 32 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 25 of the present invention;

FIG. 33 is a schematic diagram for schematically illustrating an opticalsystem of a polarization luminaire embodying the present invention,namely, Embodiment 26 of the present invention; and

FIG. 34 is a schematic diagram for schematically illustrating an opticalsystem of an example of a projection display provided with thepolarization luminaire illustrated in FIG. 31.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, modes for carrying out the present invention will bedescribed by referring to the accompanying drawings.

Incidentally, in the following description of each of embodiments of thepresent invention, same reference characters designate correspondingparts. Thus the repeated description of the corresponding parts will beavoided.

Embodiment 1

Embodiment 1 of the present invention will be described by referring toFIGS. 1(A)–(E). As shown in FIG. 1(A), a polarization luminaire 100 ofthe present invention is provided with a light source 101, a system ofthe optical integrator 102, a polarized light splitting unit 103 using aliquid crystal, and a half-wave plate 104 serving as a polarizationconversion element. The system of the optical integrator 102 comprises afirst lens plate 105 and a second lens plate 106. The polarized lightsplitting unit 103 is placed on the side of the entrance surface of thefirst lens plate 105, namely, placed to the side of the light source101. The half-wave plate 104 is formed on the exit surface of the secondlens plate 106 in such a way as to be integral therewith. Further, afield lens 107 is stuck onto the exit surface of this half-wave plate104.

As shown in FIG. 1(B), the first lens plate 105 of the system of theoptical integrator 102 is provided with a plurality of rectangular smalllenses 108. The second lens plate 106 is also provided with a pluralityof rectangular small lenses, whose number is equal to that of the lenses108 and whose shapes are similar to those of the lenses 108.

Polarized light, which is radiated from the light source 101 and has arandom polarization direction (actually considered as a mixed lightwhich comprises a p-polarized light and a s-polarized light), is made tobe incident on the polarized light splitting unit 103, whose primarycomponent is a liquid crystal, and is then split into a p-polarizedlight and an s-polarized light, which are slightly different in outgoingangle from each other, according to an outgoing angular dependence ofthis polarized light splitting unit 103, which corresponds to eachpolarized light. As shown in this figure, the polarized light is splitinto the p-polarized and s-polarized lights, whose outgoing directionsare different from each other by an angle θ. The two kinds of polarizedlights having outputted from the polarized light splitting unit 103 arethen made to be incident on the first lens plate 105 of the system ofthe optical integrator 102. Further, a pair of secondary light sourceimages comprising images of the light source one of which is representedby the p-polarized light and the other is represented by the s-polarizedlight, are formed in the proximity of the focal point of each of therectangular lenses 108 composing the first lens plate, namely, insideeach of the rectangular lenses of the corresponding second lens plate106.

The number of pairs of secondary light source images is equal to thenumber of the rectangular lenses composing the first lens plate. Here,the half-wave plate 104 is placed on the exit side of the second lensplate 106 correspondingly to each of the positions, at which thesecondary light source images are respectively formed, so that whensingle kind of the polarized lights (for example, the p-polarized light)passes through this half-wave plate 104, this polarized light undergoesa rotatory polarization and is put into a state in which the plane ofpolarization of this polarized light is complete with the plane ofpolarization of the other polarized light (for instance, the s-polarizedlight). Thereafter, the luminous flux, whose polarization directions areuniform, are collected through a field lens 107 placed to the exit sideof the first lens plate onto a region 109 to be illuminated. This region109 is almost uniformly illuminated with such luminous flux. Therefore,all of the luminous flux radiated from the light source 101 come to beincident on the region 109 in principle.

FIG. 1(C) illustrates the configuration of the polarized light splittingunit 103 in which a liquid crystal layer 111 is sandwiched between aprism substrate 112, which has serrate grooves, and a glass substrate113. Molecules of the liquid crystal are aligned in parallel with thegrooves of the prism substrate 112 (namely, are in homogeneousalignment), so that a luminous flux entering perpendicularly on thesubstrate is split into an extraordinary ray and an ordinary raycorresponding to the molecules of the liquid crystal, which areseparated directionally. It is now assumed that an unpolarized light 114entering nearly perpendicularly on the flat surface of the prismsubstrate 112 is incident on the inclined surface of the groove of theprism substrate 112 at an angle α. When the refractive index n₀ of themolecule of the liquid crystal corresponding to the ordinary ray isequal to that n₀ of the prism substrate 112 corresponding thereto, anordinary ray 116 is not refracted at the inclined surface 115 buttravels in a straight line, whereas an extraordinary ray 117 isrefracted. Thereby, there is caused an angular difference θ between thedirection in which the ordinary ray travels and the extraordinary raytravels. When n₁ denotes the refractive index of the liquid crystalcorresponding to the extraordinary ray, the following equation holdsapproximately.α=arctan{sin θ/(cos θ−n ₀ /n ₁)}

If the prism substrate 112 is made of PMMA, the refractive index thereofbecomes 1.48 or so. Thus, the refractive index of the ordinary ray tothe liquid crystal can be selected in such a way as to be nearly equalto that of the prism substrate. The angle θ can be increased withincreasing the difference of the refractive index between the ordinaryray and the extraordinary ray relative to the liquid crystal. Currently,liquid crystals, each of which has the difference of the refractiveindex of 0.25 or so, are commercially available. In the case that ametal halide lamp is used as the light source 101 for supplying anincident luminous flux, the diverging angles of output light withrespect to the principal ray range between ±5 degrees or so. Thediverging angles of output light, however, can be limited to the rangeextending from −3 to +3 degrees or so by using a lamp, whose arc lengthis short, and further contriving the optical system. Thereupon, if theangle θ between the polarized lights is at least 6 degrees, both of thepolarized lights can be completely separated from each other. The angleα determined by substituting such values for the aforementioned equationis 37 degrees. Thus, the angle formed between the flat surface and theinclined surface of the prism substrate 112 is about 37 degrees.Consequently, the prism substrate can be easily produced by usingorganic substance such as polymethylmethacrylate or polycarbonate.

Incidentally, in practice, as illustrated in FIG. 1(C), incidentluminous flux is incident on the entrance surface 118 of the prismsubstrate 112 at a regular angle θ. Thereby, the principal beams of theentire luminous flux obtained by splitting the polarized light becomesperpendicular to the polarized light splitting unit. Consequently, theentire optical system can be easily configured. An angle β is equal tothe angle θ/2. Thus, when the angle θ is 6 degrees, the angel β is 3degrees. Practically, the light source has only to be tilted slightly.

In point of the efficiency, it is better that the refractive index ofthe extraordinary ray relative to the liquid crystal is equalized withthat relative to the prism substrate 112. In the case of this method,the ordinary ray 116 is refracted. The ordinary ray, however, is ap-polarized light to be outputted from the inclined surface 115 of theprism substrate 112 and the angle of incidence on an interface is closeto Brewster angle, so that the reflection loss can be limited to 1% orless. Thus, if a anti-reflection coat is applied to the interfacebetween the prism substrate and the air, the transmittance of theluminous flux can be theoretically increased to 97% or more.

The polarized light splitting unit 103 illustrated in FIG. 1(C) is madeby using a liquid crystal. The polarized light splitting unit, however,can be produced by using an organic film, in principle. For example, theretardation film can be made at a low price if the serrate grooves areformed by being stamped. Further, it is thought that such a retardationfilm is thermally stable. Moreover, even if monomers are aligned insteadof the molecules of the liquid crystal and are polymerized by usingultraviolet rays or heat, a thermally stable polarized light splittingunit can be obtained.

In the system of the optical integrator, the shape of a rectangular lens121 is similar to that of the region 109 to be illuminated. Because ofthe oblong rectangular shape of the screen of TV, the shape of therectangular lens 121 becomes oblong rectangle in accordance with theshape of the screen of TV in the case that a system of the opticalintegrator is incorporated into a projection display.

In the case of an ordinary system of the optical integrator 102 whichdoes not use a polarized light splitting unit, a secondary light sourceimage is formed at the center of each of the rectangular lenses of thesecond lens plate 106. When the diverging angle of light emitted fromthe light source is within θ and the distance between the first lensplate 105 and the second lens plate 106 is L, the secondary light sourceimage is formed within a circular region 122 having a diameter of θL inthe central portion of each of the rectangular lenses 121, as shown inFIG. 1(D). Here, it is seen that in both sides of each of therectangular lenses 121, there are rather large areas 123 which containno secondary light source images. Thus, the polarization luminaire ofthe present invention performs-the polarization conversion by utilizingthis region 123. In the case of this embodiment, on the second lensplate 106, as shown in FIG. 1(E), two kinds of secondary light sourceimages 131 and 132 respectively corresponding to both of the two kindsof polarized lights are formed on each of the rectangular lenses 121.The distance between both of the secondary light source images is equalto the diameter θL of each of the secondary light source image, so thatthe secondary light source images are separated just as shown in thisfigure. Moreover, each of the secondary light source images goes into acorresponding one of the rectangular lenses 121. Needless to say, thephenomenon described hereinabove occurs only in the case that the regionto be illuminated is oblong. However, if the size of each of thesecondary light source image can be reduced sufficiently, such aphenomenon applies in the case that the region to be illuminated is notoblong.

As illustrated in FIG. 1(E), retardation layers 104 a and 104 bcomposing the retardation film 104 are disposed like stripes,correspondingly to the secondary light source images 131 and 132represented by the two kinds of polarized lights, respectively. It isthought that there are the cases where the planes of polarization of thepolarized lights are rotated 45 degrees by the layers 104 a and 104 b ofthis retardation film so as to make the planes of polarization of thepolarized lights extend in the same direction, and where the retardationfilm is constituted only by single kind of the retardation layer and theplane of polarization of the polarized light of only one kind is turned90 degrees by the half-wave plate 104, similarly as in the case of thisembodiment. Incidentally, in the case of this embodiment, thisretardation film 104 is sandwiched between the second lens plate 106 andthe field lens 107 and is bonded thereto as shown in FIG. 1(A), so thatthe reflection loss due to the interface can be eliminated.

Additionally, in the case of this embodiment, the polarized lightsplitting unit 103 is placed prior to the first lens plate 105. Insteadof this, the polarized light splitting unit 103 may be placed betweenthe first lens plate 105 and the second lens plate 106.

Projection Display Using Polarization Luminaire of Embodiment 1

FIG. 2 schematically illustrates the configuration of the projectiondisplay using the polarization luminaire 100 illustrated in FIGS.1(A)–(E). In FIG. 2, same reference characters designate the composingelements of the polarization luminaire 100 illustrated in FIGS.1(A)–(E).

In a projection display 200 of this example, the light source 101 is ahalogen lamp, a metal halide lamp, a xenon lamp or the like. Theluminous flux radiated therefrom are reflected by a reflection mirror101 a and thus become those of nearly parallel. Among the luminous flux,the bundle of the red rays are transmitted by a blue-and-greenreflection dichroic mirror 203, which is adapted to reflect green andblue rays, and bundles of green and blue rays are reflected thereon.Subsequently, the bundle of the red rays are reflected by a double-sidedtotal reflection mirror 206 and total reflection mirrors 210 and 211 insequence. Thereafter, the bundle of the reflected red rays reach aliquid crystal light valve 109R through a condenser lens 213. The bundleof the green rays are first reflected by a total reflection mirror 207and is next reflected by a green reflection dichroic mirror 212. Then,the bundle of the reflected green rays are further reflected by adouble-sided total reflection mirror 206. Thereafter, the bundle of thereflected green rays reach a corresponding liquid crystal light valve109G through a condenser lens 213. The bundle of the blue rays are firstreflected by a total reflection mirror 207 and are then transmitted by agreen reflection dichroic mirror 212. Next, the bundle of thetransmitted blue rays are reflected by a total reflection mirror 217.Subsequently, the bundle of the reflected blue rays are incident on aliquid crystal light valve 109B through the condenser lens 213,similarly as in the case of the bundles of other color rays. Each of thethree liquid crystal light valves 109 is adapted to modulate the bundleof rays of a corresponding color and causes the rays to contain imageinformation representing an image of the corresponding color. A dichroicprism 215 synthesizes these bundles of the modulated rays respectivelycorresponding to the colors. In the dichroic prism 215, two dielectricmulti-layer films which is adapted to reflect a bundle of red rays andthe other is adapted to reflect a bundle of blue rays, are formedcrosswise. Further, the synthetic rays pass through a projection lens216 so that an image is formed therefrom on a screen.

The system of the optical integrator 102 is disposed correspondingly tothe bundle of the rays divided by the blue-and-green reflection dichroicmirror 203. Regarding the red rays, the first lens plate 105 and thesecond lens plate 106 are placed prior to and posterior to thedouble-sided total reflection mirror 206. Regarding the bundles of thegreen and blue rays, the first lens plate 105 and the second lens plate106 are placed prior to and posterior to the total reflection mirror207. It is important that each of the total reflection mirrors is placedbetween the lens plates. A dichroic mirror may be inserted between thelens plates. In this case, bundles of rays, whose angles of incidenceare nonuniform, are incident on the dichroic mirror. Thus, owing to theangular dependence of the dielectric multi-layer film, inconsistenciesin colors are liable to occur on the screen. Further, as a result ofemploying the configuration as illustrated in FIG. 2, a substantialworking distance becomes equal to the distance from second lens plate106 to the liquid crystal light valve 109. In comparison with the casethat no system of the optical integrator is provided therein, thesubstantial working distance becomes half of that in such a case. Inpractice, the efficiency in utilizing the bundles of the rays becomesnearly twice that in the case that no system of the optical integratoris provided therein. The display nonuniformity is eliminated almostcompletely.

As described above, the liquid crystal polarized light splitting unit103 is mounted on the entrance side of the first lens plate 105 of thesystem of the optical integrator 102. Further, the half-wave plate 104serving as the polarization conversion element is disposed on the exitsurface of the second lens plate 106.

In the case of this projection optical system, the back focus of theprojection lens 216 is short. Thus, the optical system can be easilydesigned in such a manner that the numerical aperture of the projectionlens is large while the size thereof is kept small. Consequently, themaximum effects of the optical integrator can be achieved.

Further, in the case of projection displays (namely, liquid crystalprojectors) currently put to practical use, liquid crystal light valvesof the types adapted to modulate polarized light are used. Therefore,half of the nonpolarized light radiated from the light source isabsorbed by a polarizing plate and is thus converted into heat.Consequently, reduction in the efficiency in utilizing the light as wellas the necessity of cooling the polarizing plate for preventing heatbeing produced therefrom becomes a problem. However, in the case of thisexample, a polarized light converting system is added to the system ofthe optical integrator. Further, most of luminous fluxes radiated fromthe light source are converted into a single kind of polarized lightsand are utilized. Thus, the efficiency in utilizing the light isenhanced. Moreover, the polarizing plate (not shown) can be restrainedfrom producing heat.

FIGS. 3(A)–(B) illustrate another example of the configuration of theprojection display using the polarization luminaire illustrated inFIG. 1. In FIGS. 3(A)–(B), there is shown an example of the projectiondisplay using two liquid crystal light valves.

As illustrated in FIG. 3(A), in the case of a projection display 300 ofthis example, luminous flux radiated from the light source 101 passthrough the system of the optical integrator, which consists of thefirst lens plate 105 and the second lens plate 106, after reflected bythe reflection mirror 101 a. Next, a white luminous flux is divided by agreen reflection dichroic mirror 301 into a bundle of green rays and abundle of magenta rays. The bundle of green rays and the bundle ofmagenta rays are reflected by the total reflection mirror 302 and 317,respectively. Then, the reflected bundles of rays are incident on liquidcrystal light valves 109 a and 109 b through a condenser lens 313,respectively. Subsequently, the modulated bundles of rays aresynthesized by a dichroic prism for synthesizing the bundle of greenrays and the bundle of magenta rays. Thereafter, the synthetic rays areapplied through a projection lens 316 and an image is displayed.

In this configuration, there are two liquid crystal light valves. It is,thus, necessary to provide color filters in the panel of one of thelight valves and to separate and modulate two color bundles of rays.FIG. 3(B) is a diagram for illustrating the configuration of pixels ofthe liquid crystal light valve 109b. As shown in this figure, redtransmitting filters 304 and blue transmitting filters 305 are placedalternately.

This configuration uses only two liquid crystal light valves. Thus, theconfiguration of the optical system is simplified very much in contrastwith the example illustrated in FIG. 2. Moreover, a single liquidcrystal light valve is used for green light. Therefore, the resolutionof this example is hardly inferior to that of the example illustrated inFIG. 2. Furthermore, the brightness of a projected image is determinedmostly by that of the green light. Hence, the brightness of the image inthe case illustrated in FIG. 3(A) is not so inferior to that of theimage in the case of the example illustrated in FIG. 2. Consequently, inthe case of displaying an ordinary image, the use of such a simplifiedconfiguration proves almost no problem, except the case that it isnecessary to concurrently display three colors at a single pixel as inthe case of a screen of a computer system.

Incidentally, the color reproducibility of the example illustrated inFIG. 3(A) is not sufficient, namely, red and blue are reproducedinsufficiently. Thus, the spectral distribution of the light source hadbetter be regulated in such a way that the quantity of red and blue area somewhat larger than those of the ordinary cases. For example, in thecase of a three-band luminescent metal halide lamp, a halidecorresponding to each primary color is added thereto. A certain metalhalide lamp, which is currently commercially available, is filled withhalides such as lithium, thallium and indium. In this case, lithium andindium correspond to red and blue, respectively. Thus, these halideshave only to be added to the lamp in such a way that the quantities ofthese halides are a little larger than those thereof to be usuallyadded.

Metal halide lamps for displaying images, which are presentlycommercially available, have a common drawback in that red shortage isliable to occur. Thus, there can be contrived a method, by which asingle liquid crystal light valve is prepared for modulating a bundle ofred rays and a common panel is also prepared for modulating bundles ofgreen and blue rays, as an example of modification of the systemillustrated in FIG. 3(A). In contrast with an ordinary projectiondisplay which employs a method of reducing the quantity of green lightso as to make up for a shortage of red light, a method of this examplecan obtain a sufficient quantity of red light and thus can obviate thenecessity of reducing the quantity of green light. Therefore, thequantity of a projected image is nearly equal to that obtained by theaforementioned projection display, and the projection display of thisexample is suited to display an ordinary image.

The back focus of a projection lens is short in the case of theprojection display of this example as well as that of aforementionedexample. Thus, in spite of using the optical integrator, the projectiondisplay of this example can be designed in such a manner that theprojection lens is small, and the entire configuration of the projectiondisplay of this example can be simplified very much. Further, theresolution and the brightness of a projected image are not so inferiorto those obtained by the aforementioned example, and the projectiondisplay of this example is very suitable for displaying an ordinaryimage.

Embodiment 2

The polarization luminaire of Embodiment 1 employs the optical systemwhich uses a liquid crystal material as the polarized light splittingmeans. In this optical system, the efficiency in utilizing light isimproved. Thus, the polarization luminaire of Embodiment 1 excels in therespect that a bright projected image can be obtained. The refractiveindex of the liquid crystal material, however, highly depends ontemperature. Therefore, if such a liquid crystal material isincorporated into the light source system of the projection display inwhich the temperature may vary significantly, there is the fear that thepolarized light splitting angle formed between the polarized lightsobtained by splitting a light becomes unstable.

In the case of this embodiment, a luminaire being capable of stablyexerting the good performance even in the environment, in which asignificant change in temperature may occur, is realized by using aprism beam splitter, which excels in the temperature dependence of thepolarized light splitting angle, as the polarized light splitting means.

FIGS. 4(A)–(C) show plan views of the general configuration of thepolarization luminaire of this embodiment. As shown in FIG. 4(A), thepolarization luminaire 400 of this embodiment has a light source portion401, a polarized light splitting portion 402 and a system of the opticalintegrator 403, which are placed along a system optical axis L. Thisluminaire is set in such a way that light radiated from the light sourceportion 401 reaches a rectangular region 404 to be illuminated, throughthe polarized light splitting portion 402 and the system of the opticalintegrator 403.

The light source portion 401 is mostly composed of a light source lamp411 and a paraboloidal reflector 412. Polarized lights having randompolarization directions (hereunder referred to simply asrandomly-polarized lights), which are radiated from the light sourcelamp 401, are reflected by the paraboloidal reflector 412 in a singledirection and thus become a nearly parallel luminous flux that are thenincident on the polarized light splitting portion 402. Here, note thatan ellipsoidal reflector or a spherical reflector may be used in placeof the paraboloidal reflector 412.

The polarized light splitting portion 402 is an improvement overordinary beam splitters and is mostly composed of a triangle-pole-likerectangular prism (namely, a triangular prism) 421 and a flatquadrangular prism 422. In the case of this embodiment, a deviationprism 424 is optically bonded onto an exit surface 423 of the polarizedlight splitting portion 402.

As illustrated in FIG. 4(B), a polarized light splitting film 426 isformed on an inclined surface portion 425 of the rectangular prism 421.A first side-surface portion 427 of the quadrangular prism 422 isoptically bonded onto the inclined surface portion 425 of therectangular prism 421 in such a way that this polarized light splittingfilm 426 is sandwiched between these prisms. A reflection film 429 isformed on a second side-surface portion 428, which is opposite to thefirst side-surface portion 427 thereof, of the quadrangular prism 422.The polarized light splitting film 426 is formed in such a manner as tobe inclined at an angle α to a entrance surface 431 of the polarizedlight splitting portion 402. In the case of this embodiment, the angle αis 45 degrees. The reflection film 429 is formed in such a way as to beinclined at an angle θ to the polarized light splitting film 426.Incidentally, the angle α formed between the polarized light splittingfilm 426 and the entrance surface 431 is not limited to 45 degrees andmay be set according to the angle of incidence of a light flux radiatedfrom the light source portion 401.

In the case of this embodiment, the rectangular prism 421 and thequadrangular prism 422 are made of a thermally stable glass material.The polarized light splitting film 426 is constituted by a dielectricmulti-layer film made of an inorganic material. The reflection film 429is constituted by an ordinary aluminum evaporation film.

The system of the optical integrator 403 having the first lens plate 441and the second lens plate 442 is placed therein as a stage subsequent tothe polarized light splitting portion 402 and the deviation prism 424.As above described by referring to FIG. 1(B), each of the first lensplate 441 and the second lens plate 442 is a composite lens elementhaving small lenses 443 and 444 which number is equal to each other.Here, note that each of the small lenses of the first lens plate 441 hasa laterally elongated rectangular shape similar to that of the region404 to be illuminated.

Moreover, in the case of this embodiment, in the second lens plate 442,a half-wave plate 446 acting as the polarization conversion element isformed between a set of the small lenses 444 and a plano-convex lens445. The half-wave plate 446 is formed at a position at which asecondary light source image is formed by the first lens plate 441, insuch a manner as to extend in a direction perpendicular to the systemoptical axis L, after performing a process which will be describedlater. Further, retardation layers 447 formed in the half-wave plate 446are formed in such a manner as to correspond to positions at whichsecondary light source images are formed from the p-polarized lightamong the secondary images formed from the s-polarized light and thep-polarized light, with regularity.

In the polarization luminaire 400 having such a configuration,randomly-polarized lights are radiated from the light source portion 401and are then incident on the polarized light splitting portion 402, asillustrated in FIG. 4(A). The randomly-polarized lights having beenincident on the polarized light splitting portion 402 can be consideredas mixed-lights of p-polarized lights and s-polarized lights. In thepolarized light splitting portion 402, the mixed-lights are separatedlaterally (incidentally, vertically as viewed in FIG. 4(A)) by thepolarized light splitting film 426 into two kinds of polarized lights,namely, the p-polarized lights and the s-polarized lights. Namely, as-polarized light component included in the randomly-polarized light isreflected by the polarized light splitting film 426, so that a travelingdirection is changed. In contrast, a p-polarized light componentincluded therein is transmitted by the polarized light splitting film426 without any change and is first reflected by the reflection film429. Here, the reflection film 429 is formed in such a way as to beinclined at an angle θ to the polarized light splitting film 426. Thetraveling directions of the two kinds of the polarized lights are madeto be slightly different from each other by an angular difference 2 è inthe transverse direction (which corresponds to the vertical direction asviewed in FIG. 4(A), namely, corresponds to the longitudinal directionof the region 404 to be illuminated) when these polarized lights aretransmitted by the prisms made of glass materials, respectively.

Further, when exiting from the deviation prism 424, the outgoing anglesof the two kinds of the polarized lights, whose traveling directions aremade to be slightly different from each other, are set in such a waythat these polarized lights have the angles of incidence which arenearly symmetrical with respect to the system optical axis L in thetransverse direction. These polarized lights are caused to be incidenton the system of the optical integrator 403 while being in such states.

In the system of the optical integrator 403, the two kinds of thepolarized lights are incident on the first lens plate 441 and then formssecondary light source images in the second lens plate 442,respectively. At the position where the secondary light source imagesare formed, the half-wave plate 446 is placed.

Here, in the polarized light splitting portion 402, the travelingdirections of the two kinds of polarized lights are made to be slightlydifferent from each other in the transverse direction. Thus, the anglesof incidence of the two kinds of polarized lights entering the firstlens plate 441 are slightly different from each other. Therefore, asillustrating the secondary light source images formed from the two kindsof polarized lights in FIG. 4(C) in the case that the second lens plate442 is viewed from the region 404 to be illuminated, two kinds ofsecondary light source images, that is, one kind of secondary lightsource images C1 (namely, circular regions hatched with parallelslanting lines drawn from upper-left to lower-right, among circularimages) which is formed from a p-polarized light, and the other kind ofsecondary light source images C2 (namely, circular regions hatched withparallel slanting lines drawn from lower-left to upper-right, among thecircular images) which is formed from an s-polarized light, are formedside by side. Further, each of the small lenses 443 composing the firstlens plate 441 forms one secondary light source image C1 resulted from ap-polarized light and the other secondary light source images C2resulted from an s-polarized light. In contaast with this, in thehalf-wave plate 446, the retardation layer 447 is selectively formedcorrespondingly to a position where the secondary light source image C1resulted from the p-polarized light. Thus, when passing through theretardation layer 447, the p-polarized light undergoes a rotatorypolarization to be converted into the s-polarized light. On the otherhand, the s-polarized light does not pass through the retardation layer447 and thus passes through the half-wave plate 446 without undergoingthe rotatory polarization. Consequently, most of luminous fluxesradiated from the system of the optical integrator 403 are made to bes-polarized lights.

The luminous fluxes, which have been made to be s-polarized light, areapplied to the region 404 to be illuminated. Namely, images of imageplanes extracted by the small lenses 443 of the first lens plate 441 areformed at a single place by the second lens plate 442 in such a manneras to be superposed thereon. Further, when passing through the half-waveplate 446, the lights are converted into polarized lights of a singlekind. Thus most of the lights reach the region 404 to be illuminated.Consequently, the region 404 to be illuminated is uniformly illuminatedwith the polarized lights, most of which are of the single kind.

As above described, in the case of the polarization luminaire 400 ofthis embodiment, a randomly-polarized light radiated from the lightsource portion 401 is split by the polarized light splitting portion 402into two kinds of polarized lights which travel in different directions.Thereafter, each of the two kinds of polarized lights is led to apredetermined region of the half-wave plate 446, whereupon a p-polarizedlight is converted into an s-polarized light. Thus, therandomly-polarized lights radiated from the light source portion 401 canbe applied to the region to be illuminated, while most of the polarizedlights are in a state in which these beams are made to be s-polarizedlights.

Moreover, high ability of the polarized light splitting portion 402 tosplit polarized light is necessary for leading each of the two kinds ofpolarized lights to the predetermined region of the half-wave plate 446.In the case of this embodiment, the polarized light splitting portion402 is constituted by utilizing the prisms made of glass and thedielectric multi-layer film made of an inorganic material. Thus, thepolarized light splitting ability of the polarized light splittingportion 402 is thermally stable. The polarized light splitting portion402, therefore, exerts the stable polarized light splitting ability atall times even in the case that the luminaire is required to output alarge quantity of light. Consequently, the polarization luminaire havingsatisfactory ability can be realized.

Furthermore, the deviation prism 424 is bonded to the exit surface 423of the polarized light splitting portion 402 between this portion 402and the system of the optical integrator 403 and is thus formed in sucha manner as to be integral with the polarized light splitting portion402. Consequently, the loss of the light due to the optical reflectioncaused on the interface between the rectangular prism 421 and thedeviation prism 424 can be reduced.

Further, in the case of this embodiment, the two kinds of polarizedlights radiated from the polarized light splitting portion 402 areseparated in the transverse direction, so that the shapes of the smalllenses 444 of the second lens plate 442 are laterally elongatedrectangles. Thus, even in the case that the region 404 to beilluminated, whose shape is a laterally elongated rectangle, is formed,no quantity of light is wasted. Here, note that the use of the region404 to be illuminated, whose shape is a laterally elongated rectangle,has advantages in that, for example, when such a region is used fordisplaying various kinds of images, the displayed images can be seenmore easily and appeal more strongly than those whose shapes arelongitudinally elongated rectangle.

Incidentally, the plano-convex lens 445 is disposed on the exit side ofthe second lens plate 442 in order to lead luminous fluxes, which go outfrom the second lens plate 442, to the region 404 to be illuminated.Consequently, the plano-convex lens 445 can be omitted by using adecentered lens as the second lens plate 442.

Additionally, in the case of this embodiment, the retardation layer 447of the half-wave plate 446 is formed at a position where the p-polarizedlight is condensed. Conversely, the retardation layer 446 can be formedat a position where the s-polarized light is condensed. In this case,s-polarized light is converted into p-polarized light, so that thepolarized lights having been put into a state, in which the polarizedlights are made to be p-polarized lights, can be applied to the region404 to be illuminated. Further, the position, at which the half-waveplate 446 is placed, is not limited to those between the small lens 449and the plano-convex lens 445. The half-wave plate 446 may be placed atanother position as long as this position is in the vicinity of aposition where a secondary light source image is formed.

Moreover, the two retardation layers, which have differentcharacteristics, may be placed at a position at which p-polarized lightis condensed and at a position at which s-polarized light is condensed,respectively, to be made the lights that have a single specificpolarization direction.

Incidentally, in the case of this embodiment, each of the small lenses443 of the first lens plate 441 is a laterally-elongated rectangularlens. In contrast, there is no limitation to the shape of each of thesmall lenses 444 of the second lens plate 442. Incidentally, because thesecondary light source image C1, which is formed from the p-polarizedlight, and the secondary light source image C2, which is formed from thes-polarized light, are formed side by side in the transverse directionas illustrated in FIG. 4(C), the shape of each of the small lenses 444of the second lens plate 442 may be a laterally-elongated rectanglesimilar to that of each of the small lenses 443 of the first lens plate441, correspondingly to the positions where such images are formed.

Embodiment 3

In Embodiment 2, the deviation prism 424 is disposed in order to set theoutgoing direction of each of the two kinds of polarized lights to be apredetermined direction. Thus, the position, at which the deviationprism 424 is placed, is not limited to a position on the exit side ofthe polarized light splitting portion but may be a position on theentrance side thereof, namely, may be a position on the side of thelight source portion, or a position adjacent to the first lens plate ofthe system of the optical integrator.

Namely, the polarization luminaire may be configured as that ofEmbodiment 3 illustrated in FIG. 5. The basic configuration of each ofthis polarization luminaire and embodiments, which will be describedhereinbelow, is similar to that of the polarization luminaire ofEmbodiment 2. Therefore, same reference characters designate partshaving same functions. Further, the descriptions of such parts will beomitted.

In the case of a polarization luminaire 500 illustrated in FIG. 5, thedeviation prism 424 is similarly placed between the polarized lightsplitting portion 402 and the system of the optical integrator 403. Thedeviation prism 424, however, is bonded to the first lens plate 441 ofthe system of the optical integrator 403 and is formed in such a manneras to be integral with the system of the optical integrator 403.Consequently, the loss of the light due to the optical reflection causedon the interface between the deviation prism 424 and the first lensplate 441 can be reduced.

Embodiment 4

Further, similarly as in the case of a polarization luminaire 600illustrated in FIG. 6, the deviation prism 424 is placed between thepolarized light splitting portion 402 and the light source portion 401.Moreover, the deviation prism 424 is bonded to the entrance surface 431of the polarized light splitting portion 402 and may be integral withthe polarized light splitting portion 402. In this case, the loss of thelight due to the optical reflection caused on the interface between thedeviation prism 424 and the rectangular prism 421 can be reduced.Furthermore, in the case of such a configuration, the first lens plate441 of the system of the optical integrator 403 is connected to the exitsurface 423 of the polarized light splitting portion 402. Thus, thedeviation prism 424, the polarized light splitting portion 402 and thesystem of the optical integrator 403 may be formed in such a manner asto be integral with one another. In this case, the loss of the light dueto the optical reflection caused on the interface therebetween can befurther reduced.

Incidentally, the deviation prism 424 can be omitted if the direction,along which the light source portion 401 extends, is slightly inclinedto the system optical axis L, as indicated by dashed lines.

Embodiment 5

Incidentally, in the case of a polarization luminaire 700 illustrated inFIG. 7, in the polarized light splitting portion 402, the angle formedbetween the entrance surface 431 and the polarized light splitting film426 is 45 degrees. In the case that the angle formed between theentrance surface 431 and the polarized light splitting film 426 is notmore than 45 degrees, the deviation prism 424 has only to be turned to adirection that is opposite to that illustrated in FIG. 4(A). Therefore,even if the configuration of the polarized light splitting portion 402changes, it is unnecessary to change the configuration of the system ofthe optical integrator 403 which may be maintained.

Embodiment 6

In the case of a polarization luminaire 800 illustrated in FIG. 8, thedisposition or optical systems is similar to that in the case ofEmbodiment 2. The rectangular prism 421 (namely, the triangular prism),which compose the polarized light splitting portion 402 with thequadrangular prism 422, consists of a prism structure element 421G,which has six transparent plates composing the walls of this prism, andliquid 421L with which the inside of the prism structure element 421G isfilled. Thus, the cost of the rectangular prism 421 can be lowered.Further, the weight of the rectangular prism 421 can be reduced byfilling the inside of the prism structure element 421F with liquidhaving a small specific gravity as the liquid 421L.

Similarly, in the case that a portion sandwiched between the polarizedlight splitting film 426 and the reflection film 429, namely, the insideof the quadrangular prism 422 is filled with transparent liquid, thecost and weight of the quadrangular prism can be reduced.

Embodiment 7

The polarized light splitting portion 402 of a polarized light splittingdevice 900 illustrated in FIG. 9 uses a plate-like quadrangular prism422 that has two opposite side-surface portions, namely, a firstside-surface portion 921, on which the polarized light splitting film426 is formed, and a second side-surface portion 922 on which areflection film 429 is formed. Inclined surface portions 911A, 9111B,911C and 911D of small rectangular prisms (namely, triangular prisms)91A, 911B, 91C and 91D are bonded to the first side-surface portion 921of the quadrangular prism 422 in such a manner that the polarized lightsplitting film 426 is sandwiched between the first side-surface portion921 and each of the inclined surface portions 911A, 9111B, 911C and911D. Small deviation prisms 90A, 90B, 90C and 90D are bonded to theexit surface of the polarized light splitting portion 402, namely, tothe exit surface of each of the rectangular prisms 91A, 91B, 91C and91D. Here, note that the number of the rectangular prisms 91A, 911B, 91Cand 91D is not necessarily equal to that of the small lenses 443 alignedin the direction of width of the first lens plate 411.

With such a configuration in which the rectangular prisms 91A to 91D andthe deviation prisms 90A to 90D can be small in size in spite of a largenumber of these prisms, the weight and cost of the entire device can bereduced.

Embodiment 8

The polarized light splitting portion 402 of a polarization luminaire1000 illustrated in FIG. 10 has: a first plate-like quadrangular prism422 that has two opposite side-surface portions, namely a firstside-surface portion 427, on which the polarized light splitting film426 is formed, and a second side-surface portion 428 on which areflection film 429 is formed; and a second quadrangular prism 422Awhich is integral with the first quadrangular prism 422 in such a waythat the polarized light splitting film 426 is sandwiched between thefirst quadrangular prism 422 and the second quadrangular prism 422A. Inthe case of the polarization luminaire 1000 constructed this way, thepolarized light splitting portion 402 can be composed of first andsecond thin quadrangular prisms 422 and 422A. Consequently, the weightof this portion can be reduced.

Embodiment 9

The polarized light splitting portion 402 of a polarization luminaire1100 illustrated in FIG. 11 uses a first triangular prism 1102, on theinclined surface of which the polarized light splitting film 426 isformed, and a second triangular prism 1104, on the inclined surface ofwhich the reflection film 429 is formed. The first triangular prism 1102and the second triangular prism 1104 are fixed by using frames (notshown) or the like in such a way that there is formed a predeterminedgap G between the inclined surface portion 1101 (on which the polarizedlight splitting film 426 is formed) and the inclined surface portion1103 (on which the reflection film 429 is formed), and are integral witheach other. Hereat, the inside of the gap G is filled with liquid H.Moreover, the liquid H is held in the gap G by a sealing compound 1105.

In the case of the polarization luminaire 1100 constructed in thismanner, the gap G can be arbitrarily narrowed, differently from the casethat a gap between the polarized light splitting film 426 and thereflection film 429 is secured and a predetermined angle θ is formed byutilizing the thickness of the prism as in Embodiment 2 or 8. Thus thisembodiment has an advantage in that the loss of light can be decreased.

Embodiment 10

FIGS. 12(A)–(B) are diagrams for schematically illustrating a plan viewof the configuration of a primary part of a polarization luminaire ofEmbodiment 10 and for illustrating an external view of the configurationof prisms used in the polarized light splitting portion of thispolarization luminaire.

As shown in FIG. 12(A), similarly as in the case of the polarizationluminaire of Embodiment 2, the polarization luminaire 1200 of thisembodiment has a light source portion 401, a polarized light splittingportion 1201 and a system of the optical integrator 403, which areplaced along a system optical axis L. This luminaire is established insuch a manner that light radiated from the light source portion 401reaches a rectangular region 404 to be illuminated, through thepolarized light splitting portion 1201 and the system of the opticalintegrator 403. Incidentally, the light source portion 401 faces therectangular region 404 to be illuminated, and the entire system opticalaxis L is shaped like a straight line.

Similarly as in the case of Embodiment 2, the light source portion 401is established in such a manner that randomly-polarized lights radiatedfrom the light source lamp 411 are reflected by a paraboloidal reflector412 in a single direction and thus become a nearly parallel luminousflux that is then incident on the polarized light splitting portion1201. Here, note that the light source portion 401 faces in a directionthat is tilted at a predetermined angle to the system optical axis L.

The polarized light splitting portion 1201 is composed ofsquare-pole-like prism composite elements 1205A, 1205B, 1205C and 1205D,each of which consists of first and second rectangular prisms 1202 and1203 (namely, triangular prisms) and a flat quadrangular prism 1204.

As shown in FIG. 12(B), in the case of each of the prism compositeelements 1205A to 1205D, the polarized light splitting film 426 isformed on one of the two opposed side-surface portions 1211 and 1212 ofthe quadrangular prism 1204, namely, on the first side-surface portion1211. Further, the reflection film 429 is formed on the secondside-surface portion 1212. The inclined surface portion 1221 of thefirst rectangular prism 1202 is bonded to the first side-surface portion1211 of the quadrangular prism 1204 in such a way that the polarizedlight splitting film 426 is sandwiched between the portions 1211 and1221. Furthermore, the inclined surface portion 1231 of the secondrectangular prism 1203 is bonded to the second side-surface portion 1212of the quadrangular prism 1204 in such a way that the reflection film429 is sandwiched between the portions 1212 and 1231. Incidentally, theprism composite element 1205E has only the function of reflection therandomly-polarized light radiated from the light source portion 401.Thus, the polarized light splitting film 426 is not formed therein.Therefore, an optical component having another reflection function maybe used instead of the prism composite element 1205E.

The square-pole-like prism composite elements 1205A to 1205E, which areconfigured in this manner, face in the same direction and are aligned ina line in the transverse direction that is perpendicular to the systemoptical axis L. Therefore, among the prism composite elements 1205A to1205D, the polarized light splitting films 426 are parallel to oneanother and similarly, the reflection films 429 are parallel to oneanother.

Hereat, each of the polarized light splitting films 426 is formed insuch a manner as to be inclined at an angle α to the entrance surface ofthe polarized light splitting portion 1201. In the case of thisembodiment, the angle α is 45 degrees. Each of the reflection films 429is formed in such a way as to be tilted at the angle θ to acorresponding one of the polarized light splitting films 426.

In the case of this embodiment, the first and second rectangular prisms1202 and 1203 and the quadrangular prism 1204 are made of thermallystable glass materials. The polarized light splitting film 426 is madeof a dielectric multi-layer film. The reflection film 429 is made of anordinary aluminum evaporation film.

Referring again to FIG. 12(A), in the case of this embodiment, adirection in which a polarized light emitted from the polarized lightsplitting portion 1201 is regulated by directing the light sourceportion 401 in a direction which is tilted at a predetermined angle tothe system optical axis L. Thus, a deviation prism is omitted.

In the case of this embodiment, as will be described later, a lightradiated from the light source portion 401 passes through the polarizedlight splitting portion 1201 by being shifted in the transversedirection (namely, in the upward direction as viewed in FIG. 12(B)) by adistance which correspond to the width of each of the prism compositeelements 1205A to 1205E. Therefore, the light source portion 401 isplaced by being shifted in a direction (namely, in the downwarddirection as viewed in FIG. 12(B)), which is opposite to the directionin which the light is shifted, from the system optical axis L by adistance which correspond to the width of each of the prism compositeelements 1205A to 1205E.

The system of the optical integrator comprising two lens plates, namely,the first lens plate 441 and the second lens plate 442 is disposed in astage subsequent to the polarized light splitting portion 1201. Each ofthe first lens plate 441 and the second lens plate 442 is a compositelens element provided with small lenses 443 and small lenses 444 whosenumbers are equal to each other. Each of the small lenses 443 is arectangle correspondingly to the region 404 to be illuminated and has ashape similar to that of the region 404. Moreover, in the second lensplate 442, the half-wave plate 446 is formed between the small lenses444 and the plano-convex lens 451 which is placed on the exit side. Inthe half-wave plate 446, the retardation layers 447 are formed atpositions where secondary light source images are formed by the firstlens plate 441. Further, the retardation layers 447 are regularly formedat positions, at each of which a secondary light source image is formedfrom one of an s-polarized light and a p-polarized light, namely, formedfrom the p-polarized light.

In the polarization luminaire 1200 having such a configuration,randomly-polarized lights are radiated from the light source portion 401and are then incident on the polarized light splitting portion 402. Therandomly-polarized lights having been incident on the polarized lightsplitting portion 402 are first reflected in the transverse direction bythe reflection film 429. Then, the reflected lights are incident on theadjoining prism composite elements 1205A to 1205D. Here, therandomly-polarized lights can be considered as mixed-lights ofp-polarized lights and s-polarized lights. Thus, the mixed-lights areseparated laterally by the polarized light splitting film 426 into twokinds of polarized lights, namely, the p-polarized lights and thes-polarized lights. Namely, an s-polarized light component, which isincluded in the randomly-polarized light shifted to the prism compositeelements 1205A to 1205D, is reflected by the polarized light splittingfilm 426, so that a traveling direction, in which the s-polarized lightcomponent travels, is changed. In contrast, a p-polarized lightcomponent included therein is transmitted by the polarized lightsplitting film 426 without any change and is first reflected by thereflection film 429. Here, the reflection film 429 is formed in such away as to be inclined at an angle θ to the polarized light splittingfilm 426. The traveling directions of the two kinds of the polarizedlights are made to be slightly different from each other by an angulardifference 2 è in the transverse direction when these polarized lightsare transmitted by the prisms made of glass materials, respectively.

Further, the two kinds of the polarized lights, whose travelingdirections are made to be different from each other, are caused to beincident on the system of the optical integrator 403.

In the system of the optical integrator 403, the two kinds of thepolarized lights, whose traveling directions are made to be slightlydifferent from each other, are incident on the first lens plate 441 andthen forms secondary light source images in the second lens plate 442,respectively. At the position where the secondary light source imagesare formed, the half-wave plate 446 is placed. Moreover, in thehalf-wave plate 446, the retardation layers 447 are selectively formedcorrespondingly to the positions where the secondary light source imagesare formed from the p-polarized lights. Thus, when passing through theretardation layers 447, the p-polarized lights undergo the rotatorypolarization, so that the p-polarized light is converted intos-polarized light. On the other hand, the s-polarized light does notpass through the retardation layer 447 and thus passes through thehalf-wave plate 446 without undergoing the rotatory polarization.Consequently, most of light fluxes radiated from the system of theoptical integrator 403 are made to be s-polarized lights. The fluxes ofs-polarized lights obtained in this way are applied to the region 404 tobe illuminated, by means of the decentered lens 1231.

As above described, in the case of the polarization luminaire 1200 ofthis embodiment, after a randomly-polarized light radiated from thelight source portion 401 is split by the polarized light splittingportion 1201 into two kinds of polarized lights which travel indifferent directions, each of the two kinds of polarized lights is ledto a predetermined region of the half-wave plate 446, whereupon ap-polarized light is converted into an s-polarized light. Thus, thepolarization luminaire 1200 of this embodiment exerts the effects inthat the randomly-polarized lights radiated from the light sourceportion 401 can be applied to the region 404 to be illuminated, whilemost of the polarized lights are in a state in which they are made to bes-polarized lights. Here, note that high ability of the polarized lightsplitting portion 1201 to split polarized light is necessary for leadingeach of the two kinds of polarized lights to the predetermined region ofthe half-wave plate 446. However, in the case of this embodiment, thepolarized light splitting portion 1201 is constituted by utilizing theprisms made of glass and the dielectric multi-layer film. Thus, thepolarized light splitting ability of the polarized light splittingportion 1201 is thermally stable. The polarized light splitting portion1201, therefore, exerts the stable polarized light splitting ability atall times even in the case that the luminaire is required to output alarge quantity of light. Consequently, the polarization luminaire havingsatisfactory ability can be realized.

Furthermore, in the case of this embodiment, the two kinds of polarizedlights radiated from the polarized light splitting portion 1201 areseparated in the transverse direction. Thus, the small lenses 444 of thesecond lens plate 442 are formed in such a manner that the shapesthereof are laterally elongated rectangles. Consequently, the region 404to be illuminated, whose shape is a laterally elongated rectangle, canbe formed without wasting any quantity of light. Here, note that the useof the region 404 to be illuminated, whose shape is a laterallyelongated rectangle, has advantages in that, for example, when such aregion is used for displaying various kinds of images, the displayedimages are seen easily and appeal strongly in comparison with the caseof using a projection pattern whose shape is a laterally elongatedrectangle.

Example of Modification of Embodiment 10

Incidentally, Embodiment 10 is in a condition in which the width of eachof the small lenses 44 of the first lens plate 441 is equal to that ofeach of the quadrangular prisms composite elements 1205A to 1205E.Namely, assuming that the width W1 of each of the prism compositeelements 1205A to 1205E is expressed as (1/n) times the width W2 of eachof the rectangular lenses 443 of the first lens plate 441 where n is aninteger equal to or more than 1, such a condition is equivalent to thecondition that n is equal to 1. As n is gradually increased to 2, 3, . .. , the width of each of the prism composite elements 1205A to 1205E isdecreased. Thus, the thickness of each of the prism composite elements1205A to 1205E can be reduced.

For example, when n is set at 2, the polarized light splitting portion1201 of the polarization luminaire 1250 becomes configured asillustrated in FIG. 13. Namely, the width W1 of each of thesquare-pole-like prism composite elements 1205A, 1205B, 1205C, . . . isas ½ times as the width W2 of each of the rectangular lenses 443 of thefirst lens plate 441. In this case, the thickness of the polarized lightsplitting portion 1201 can be reduced. Moreover, the distance X, bywhich the light source portion 401 is shifted from the system opticalaxis L, can be decreased.

In contrast, in the case of the embodiment illustrated in FIG. 12s(A)–(B), the polarized light slitting portion 1201 is placed in thelight source portion of the first lens plate 441. Instead of this, thepolarized light slitting portion 1201 may be disposed between the firstlens plate 441 and the second lens plate 442.

Embodiment 11

FIG. 14 is a schematic diagram for schematically illustrating a planview of a primary part of a polarization luminaire of Embodiment 11.Similarly as in the case of the polarization luminaire of Embodiment 2,the polarization luminaire 1400 of this embodiment has a light sourceportion 401, a polarized light splitting portion 1401 and a system ofthe optical integrator 403, which are placed along a system optical axisL. This luminaire is established in such a manner that light radiatedfrom the light source portion 401 reaches a rectangular region 404 to beilluminated, through the polarized light splitting portion 1401 and thesystem of the optical integrator 403. Incidentally, the light sourceportion 401 faces the rectangular region 404 to be illuminated, and theentire system optical axis L is shaped like a straight line.

Similarly as in the case of Embodiment 2, the light source portion 401is established in such a manner that randomly-polarized lights radiatedfrom the light source lamp 411 are reflected by a paraboloidal reflector412 in a single direction and thus become a nearly parallel luminousflux that are then incident on the polarized light splitting portion1401.

The polarized light splitting portion 1401 is composed ofsquare-pole-like prism composite elements 1404A, 1404B, 1404C and 1404D,each of which comprises first and second rectangular prisms 1402 and1403 (namely, triangular prisms).

In the case of each of the prism composite elements 1404A to 1404E, thepolarized light splitting film 426 is formed on an inclined surfaceportion 1411 of the first rectangular prism 1402. The inclined surfaceportion 1412 of the second rectangular prism 1403 is bonded to theinclined surface portion 1411 of the first rectangular prism 1402 insuch a way that the polarized light splitting film 426 is sandwichedbetween the portions 1411 and 1412. Incidentally, the prism compositeelement 1404A has only the function of reflecting s-polarized lightseparated by the prism composite element 1404B.

The square-pole-like prism composite elements 1404A to 1404E, which areconfigured in this manner, face in the same direction and are aligned ina line in the transverse direction that is perpendicular to the systemoptical axis L. Incidentally, in the case of this embodiment, the prismcomposite elements 1404A to 1404E have the same width but are differentin thickness from one another. Therefore, the angles, which the prismcomposite elements 1404B to 1404E respectively make with the entrancesurface 1421 of the polarized light splitting portion 1401, are slightlydifferent from one another.

In the case of this embodiment, the first and second rectangular prisms1402 and 1403 are made of thermally stable glass materials. Thepolarized light splitting film 426 is made of a dielectric multi-layerfilm.

Although a direction, in which the polarized light radiated from thepolarized light splitting portion 1401 travels, may be regulated byusing a deviation prism, such a direction, in which the polarized lightradiated from the polarized light splitting portion 1401, is regulatedin this embodiment by directing the light source portion 401 in adirection which is tilted at a predetermined angle to the system opticalaxis L. Thus, the deviation prism is omitted from this embodiment.

Further, similarly as in the case of Embodiment 10, a light radiatedfrom the light source portion 401 passes through the polarized lightsplitting portion 1401 by being shifted in the transverse direction(namely, in the upward direction as viewed in FIG. 14) by a distance,which correspond to the width of each of the prism composite elements1404A to 1404E, in the polarized light splitting portion 1401.Therefore, in the case of this embodiment, the light source portion 401is placed by being shifted in a direction (namely, in the downwarddirection as viewed in FIG. 14), which is opposite to the direction inwhich the light is shifted, from the system optical axis L by a distancewhich correspond to the width of each of the prism composite elements1404A to 1404E.

The system of the optical integrator comprising two lens plates, namely,the first lens plate 441 and the second lens plate 442 is disposed in astage subsequent to the polarized light splitting portion 1404. Each ofthe lens plate 441 and the second lens plate 442 is a composite lenselement provided with small lenses 443 and small lenses 444 whosenumbers are equal to each other. Each of the small lenses 443 of thefirst lens plate 441 is rectangular correspondingly to the region 404 tobe illuminated and has a shape similar to that of the region 404 to beilluminated. Incidentally, among the small lenses 443 of the first lensplate 441, only p-polarized or s-polarized light is incident on thesmall lenses 443A placed both ends thereof (namely, hatched smalllenses). Thus, directions, in which the p-polarized or s-polarizedlights are radiated from the small lenses 443A thereof, are made to bedifferent from the directions in which the p-polarized or s-polarizedlights are radiated from other parts thereof.

In the case of this embodiment, in the second lens plate 442, thehalf-wave plate 1430 is formed between the small lenses 444 and theplano-convex lens 445 which placed on the exit side. In the half-waveplate 1430, the retardation layers 1431 are regularly formed atpositions, at each of which a secondary light source image is formedfrom one of an s-polarized light and a p-polarized light, namely, formedfrom the p-polarized light.

In the polarization luminaire 1400 having such a configuration,randomly-polarized lights are radiated from the light source portion 401and are then incident on the polarized light splitting portion 1401. Therandomly-polarized lights having been incident on the polarized lightsplitting portion 1401 are separated in the transverse direction by thepolarized light splitting film 426 into two kinds of polarized lights,namely, p-polarized and s-polarized lights.

This principle will be explained hereunder by describing the case ofapplying the principle to randomly-polarized lights, which have beenincident on a prism composite element 1404C, by way of example. First,an s-polarized light component included in the randomly-polarizedlights, which have been incident on a prism composite element 1404C, isreflected by the polarized light splitting film 426 and thus thedirection, in which the s-polarized light component travels, is changed.Then, the s-polarized light component is incident on the adjacent prismcomposite element 1404B. Next, the s-polarized light component isreflected by the polarized light splitting film 426 in the prismcomposite element 1404B. Subsequently, the s-polarized light componentis radiated from the polarized light splitting portion 1401. On theother hand, a p-polarized light component included in therandomly-polarized lights is transmitted by the polarized lightsplitting film 426 in the prism composite element 1404C without beingchanged. Here, in the prism composite elements 140413 to 1404E, theangles that the polarized light splitting films 426 make with theentrance surface 1421 of the polarized light splitting portion 1401 areslightly different from one another by an angle θ′. Thus, in the prismsmade of glass materials, the lateral difference between the travelingdirections of the polarized lights of the two kinds becomes larger by aslight angle.

The two kinds of the polarized lights, whose traveling directions aremade to be different from each other, are caused to be incident on thesystem of the optical integrator 403.

In the system of the optical integrator 403, the two kinds of thepolarized lights, whose traveling directions are made to be slightlydifferent from each other, are incident on the first lens plate 441 andthen forms secondary light source images in the second lens plate 442,respectively. At the position where the secondary light source imagesare formed, the half-wave plate 1430 is formed. Moreover, in thehalf-wave plate 1430, the retardation layers 1431 are selectively formedcorrespondingly to the positions where the secondary light source imagesare formed from the p-polarized lights. Thus, when passing through theretardation layers 1431, the p-polarized lights undergo the rotatorypolarization, so that the p-polarized light is converted intos-polarized light. On the other hand, the s-polarized light does notpass through the retardation layer 1431 and thus passes through thehalf-wave plate 1430 without undergoing the rotatory polarization.Consequently, most of luminous fluxes radiated from the system of theoptical integrator 403 are made to be s-polarized lights. The fluxes ofthe s-polarized lights obtained in this way are applied to the region404 to be illuminated, by means of the decentered lens 1231.

As above described, in the case of the polarization luminaire 1400 ofthis embodiment, after a randomly-polarized light radiated from thelight source portion 401 is split by the polarized light splittingportion 1401 into two kinds of polarized lights which travel indifferent directions, each of the two kinds of polarized lights is ledto a predetermined region of the half-wave plate 1430, whereupon ap-polarized light is converted into an s-polarized light. Thus, thepolarization luminaire 1400 of this embodiment exerts the effects inthat the randomly-polarized lights radiated from the light sourceportion 401 can be applied to the region 404 to be illuminated, whilemost of the polarized lights are in a state in which these beams aremade to be s-polarized lights. However, in the case of this embodiment,the polarized light splitting portion 1401 is constituted by utilizingthe prisms made of glass and the dielectric multi-layer film. Thus, thepolarized light splitting ability of the polarized light splittingportion 1401 is thermally stable. The polarized light splitting portion1401, therefore, exerts the stable polarized light splitting ability atall times even in the case that the luminaire is required to output alarge quantity of light. Consequently, the polarization luminaire havingsatisfactory ability can be realized.

Furthermore, in the case of this embodiment, the two kinds of polarizedlights radiated from the polarized light splitting portion 1401 areseparated in the transverse direction. Thus, this embodiment is suitablefor forming the region 404 to be illuminated, whose shape is a laterallyelongated rectangle.

Incidentally, in the case of this embodiment, the polarized lightsplitting portion 1401 is placed between the first lens plate 441 andthe light source portion. Instead of this, the polarized light splittingportion 1401 may be placed between the first lens plate 441 and thesecond lens plate 442.

Embodiment 12

FIG. 15 is a schematic diagram for schematically illustrating a planview of a primary part of the polarization luminaire of Embodiment 12.As shown in this figure, similarly as in the case of the polarizationluminaire of Embodiment 10, the polarization luminaire 1500 of thisembodiment has a light source portion 401, a polarized light splittingportion 1501 and a system of the optical integrator 403, which areplaced along a system optical axis L. This luminaire is established insuch a manner that light radiated from the light source portion 401reaches a rectangular region 404 to be illuminated, through thepolarized light splitting portion 1501 and the system of the opticalintegrator 403. The light source portion 401 faces the rectangularregion 404 to be illuminated, and the entire system optical axis L isshaped like a straight line. In this embodiment, a direction, in whichthe polarized light emitted from the polarized light splitting portion1501 travels, is similarly regulated by directing the light sourceportion 401 in a direction which is tilted at a predetermined angle tothe system optical axis L. Thus, the deviation prism is omitted fromthis embodiment.

The polarized light splitting portion 1501 is composed ofsquare-pole-like prism composite elements 1504A, 1504B, 1504C, 1504D,1504E and 1504F, each of which comprises first and secondtriangle-pole-like rectangular prisms 1502 and 1503 (namely, triangularprisms).

In the case of each of the prism composite elements 1404A to 1404E, thepolarized light splitting film 426 is formed on an inclined surfaceportion 1510 of the first rectangular prism 1502. The inclined surfaceportion 1511 of the second rectangular prism 1503 is bonded to theinclined surface portion 1510 of the first rectangular prism 1502 insuch a way that the polarized light splitting film 426 is sandwichedbetween the portions 1510 and 1511.

In the case of the prism composite elements 1504A to 1504E, which areconfigured in this manner, the polarized light splitting films 426disposed on a side of the system optical axis L are opposite to thosedisposed on the other side of the axis L. Namely, when viewed from thelight source portion 401, the splitting films 426 disposed on the rightside of the system optical axis L face outwardly. Similarly, thesplitting films 426 disposed on the left side of the system optical axisL face outwardly. Further, the prism composite elements 1504A to 1504Fhave the same width but are different in thickness from one another.Therefore, the angles, which of the polarized light splitting films ofthe prism composite elements 1504B to 1504E respectively make with theentrance surface 1530 of the polarized light splitting portion 1501, aredifferent from one another. Incidentally, the prism composite elements1504A and 1504F have only the function of reflecting s-polarized lightsseparated by the prism composite elements 1504B and 1504E, respectively.

In the case of this embodiment, the first and second rectangular prisms1502 and 1503 are made of thermally stable glass materials. Thepolarized light splitting films 426 are made of a dielectric multi-layerfilm.

The system of the optical integrator 403 comprising two lens plates,namely, the first lens plate 441 and the second lens plate 442 isdisposed in a stage subsequent to the polarized light splitting portion1501. Each of the lens plate 441 and the second lens plate 442 is acomposite lens element provided with small lenses 443 and small lenses444 whose numbers are equal to each other. Each of the small lenses 443of the first lens plate 441 is rectangular correspondingly to the region404 to be illuminated and has a shape similar to that of the region 404to be illuminated. Incidentally, among the small lenses 443 of the firstlens plate 441, only s-polarized light is incident on the small lenses443A placed both ends thereof (namely, hatched small lenses). Thus,directions, in which the s-polarized lights are emitted from the smalllenses 443A thereof, are made to be different from the directions inwhich the s-polarized lights are emitted from other parts thereof.

In the case of this embodiment, in the second lens plate 442, thehalf-wave plate 1550 is formed between the small lenses 444 and theplano-convex lens 445 which is placed on the exit side. In the half-waveplate 1550, the retardation layers 1551 are formed at positions, at eachof which a secondary light source image is formed from one of ans-polarized light and a p-polarized light, namely, formed from thep-polarized light.

In the polarization luminaire 1500 having such a configuration,randomly-polarized lights are radiated from the light source portion 401and are then incident on the polarized light splitting portion 1501. Therandomly-polarized lights having been incident on the polarized lightsplitting portion 1501 are separated in the transverse direction intotwo kinds of polarized lights, namely, p-polarized and s-polarizedlights. Here, in the prism composite elements 1504B to 1504E, the anglesthat the polarized light splitting films 426 make with the surface 1530of incidence of the polarized light splitting portion 1501 are slightlydifferent from one another by an angle θ′. Thus, in the prisms made ofglass materials, the lateral difference between the traveling directionsof the polarized lights of the two kinds becomes larger by a slightangle. Further, the two kinds of the polarized lights, whose travelingdirections are made to be different from each other, are caused to beincident on the system of the optical integrator 403. In the system ofthe optical integrator 403, the two kinds of the polarized lights, whosetraveling directions are made by the polarized light splitting portion1501 to be slightly different from each other, are incident on the firstlens plate 441 and then forms secondary light source images in thesecond lens plate 442, respectively. The retardation layers 1551 areselectively formed correspondingly to the positions where the secondarylight source images are formed from the p-polarized lights, among thepositions where the secondary images are formed. Thus, when passingthrough the retardation layers 1551, the p-polarized lights undergo therotatory polarization, so that the p-polarized light is converted intos-polarized light. On the other hand, the s-polarized light does notpass through the retardation layer 1551 and thus passes through thehalf-wave plate 1550 without undergoing the rotatory polarization.Consequently, most of luminous fluxes radiated from the system of theoptical integrator 403 are made to be s-polarized lights. The fluxes ofthe s-polarized lights obtained in this way are applied to the region404 to be illuminated, by means of the plano-convex lens 445.

As above described, in the case of the polarization luminaire 1500 ofthis embodiment, after a randomly-polarized light radiated from thelight source portion 401 is split by the polarized light splittingportion 1501 into two kinds of polarized lights which travel indifferent directions, each of the two kinds of polarized lights is ledto a predetermined region of the half-wave plate 1550, whereupon ap-polarized light is converted into an s-polarized light. Thus, thepolarization luminaire 1500 of this embodiment exerts the effects inthat the randomly-polarized lights radiated from the light sourceportion 401 can be applied to the region 404 to be illuminated, whilemost of the polarized lights are in a state in which these beams aremade to be s-polarized lights. Further, in the case of this embodiment,the polarized light splitting portion 1501 is constituted by utilizingthe prisms made of glass and the dielectric multi-layer film. Thus, thepolarized light splitting ability of the polarized light splittingportion 1501 is thermally stable. The polarized light splitting portion1501, therefore, exerts the stable polarized light splitting ability atall times even in the case that the luminaire is required to output alarge quantity of light. Consequently, the polarization luminaire havingsatisfactory ability can be realized.

Furthermore, in the case of this embodiment, the two kinds of polarizedlights radiated from the polarized light splitting portion 1501 areseparated in the transverse direction. Thus, this embodiment is suitablefor forming the region 404 to be illuminated, whose shape is a laterallyelongated rectangle.

Incidentally, in the case of this embodiment, the polarized lightsplitting portion 1501 is placed between the first lens plate 441 andthe light source portion. Instead of this, the polarized light splittingportion 1501 may be placed between the first lens plate 441 and thesecond lens plate 442.

Example of Protection Display Using Polarization Luminaire of Embodiment10

The aforementioned polarization luminaries of Embodiments 2 to 12 can beused in projection displays provided with liquid crystal light valves.

FIG. 16 illustrates an example of application of the luminaire ofEmbodiment 10 to a projection display (namely, a liquid crystalprojector).

As shown in this figure, a projection display 1600 is provided with thelight source portion 401. In the polarized light splitting portion 1201,a randomly-polarized light radiated from this light source portion 401is separated into two kinds of polarized lights. Between the two kindsof polarized lights, a p-polarized light is converted by the half-waveplate 446 of the system of the optical integrator 403 into ans-polarized light.

Among a flux of lights radiated from such a polarization luminaire 1600,red rays are transmitted by and blue and green rays are reflected by theblue-and-green reflection dichroic mirror 1601. Then, the red rays arereflected by a reflection mirror 1602 and thus reaches a first liquidcrystal light valve 1603. On the other hand, between the blue and greenrays, the green rays are reflected by a green reflection dichroic mirror1604 and thus reaches a second liquid crystal light valve 1605.

Here, note that blue light has optical path length longer than that ofthe other two colors (incidentally, the optical path length of red lightis equal to that of green light). Thus, a light guiding means 1650constituted by a relay lens system comprising an entrance side lens1606, a relay lens 1608 and an exit side lens 1610 is provided for bluerays. Namely, after transmitted by a green reflection dichroic mirror1604, the blue light is first led to the relay lens 1608 through thelens 1606 and by way of a reflection mirror 1607. Then, after convergedinto this relay lens 1608, the blue light is led to the exit side lens1610 by way of a reflection mirror 1609. Thereafter, the blue lightreaches a third liquid crystal light valve 1611. Hereat, the first tothird liquid crystal light valves 1603, 1605 and 1611 modulatecorresponding color rays. Subsequently, the modulated color rays aremade to be incident on a dichroic prism (namely, a color synthesismeans) 1613. The dichroic prism 1613 has a red reflection dielectricmulti-layer film and a blue reflection dielectric multi-layer film thatare arranged crosswise therein and synthesize bundles of modulated raysof such colors, respectively. The bundles of rays synthesized thereinpass through a projection lens 1614 (namely, a projection means) andcome to form images on a screen 1615.

The projection display configured in this way uses liquid crystal lightvalves, each of which is a light valve of the type that modulatespolarized light of a single kind. Thus, the projection display 1600 ofthis embodiment resolves substantial part of the problems of aconventional luminaire in that if randomly-polarized light is led to aliquid crystal light valve by using the conventional luminaire, half ofthe randomly-polarized light is absorbed by a polarizing plate and isconverted into heat and thus the efficiency in utilizing the light islow and in that a large cooling device which makes a great deal of noisefor controlling heat emitted from the polarizing plate is needed.

Namely, in the case of the projection display 1600 of this embodiment,the rotatory polarization is exerted only on one of the two kinds ofpolarized light (for instance, p-polarized light) by the half-wave plate446 in the polarization luminaire 1200 so that the plane of polarizationthereof is made to extend in the same direction as in which the otherkind of polarized light. Thus, the polarized lights, whose polarizationdirections are uniform, are led to the first to third liquid crystallight valves 1603, 1605 and 1611. Consequently, the efficiency inutilizing the light can be enhanced. Moreover, a bright projected imagecan be obtained. Further, the quantity of light absorbed by thepolarizing plate (not shown) can be reduced. Thereby, a rise intemperature of the polarizing plate can be suppressed. Consequently, itis can be realized that a cooling device is made small and its noise canbe reduced. Furthermore, in the polarization luminaire 1200, a thermallystable dielectric multi-layer is used as the polarized light splittingfilm. The ability of the polarized light splitting portion 1201 to splitpolarized light is thermally stable. The polarized light splittingportion, therefore, exerts the stable polarized light splitting abilityat all times even in the case of the projection display 1600 required tooutput a large quantity of light.

Besides, in the polarization luminaire 1200, the two kinds of polarizedlights radiated from the polarized light splitting portion 1201 areseparated in the transverse direction. Thus, the region to beilluminated, whose shape is a laterally elongated rectangle, can beformed without wasting any quantity of light. Consequently, thepolarization luminaire 1200 is suitable for a laterally elongated liquidcrystal light valve which can project an image which is easy to see andappeals strongly.

In addition, this embodiment uses a dichroic prism 1613 as the colorsynthesis means. Thus, the size of the device can be reduced. Moreover,the length of the optical path between the projection lens 1614 and eachof the liquid crystal light valves 1603, 1605 and 1611 is short. Thus,in the case of the device of this embodiment, a bright projected imagecan be realized even if a projection lens having a relatively smalldiameter is used. Further, in the case of this embodiment, the lightguiding means 1650 constituted by the relay lens system comprising theentrance side lens 1606, the relay lens 1608 and the exit side lens 1610is provided for blue rays. Consequently, irregularities in colors or thelike do not occur in projected images.

Example of Projection Display Using Polarization Luminaire of Embodiment2

In the projection display, the color synthesis means may be constitutedby an optical system using mirrors, as illustrated in FIG. 17. Thepolarization luminaire 400 illustrated in FIGS. 4(A)–(C) is used in theprojection display 1700 illustrated in FIG. 17. In the case of thispolarization luminaire 400, in the polarized light splitting portion402, a randomly-polarized light radiated from this light source portion401 is separated into two kinds of polarized lights. Between the twokinds of polarized lights, a p-polarized light is converted by thehalf-wave plate 446 of the system of the optical integrator 403 into ans-polarized light.

Among a flux of lights radiated from such a polarization luminaire 400,first, red rays are reflected by a red reflection dichroic mirror 1701and blue and green rays are transmitted. Then, the red rays arereflected by a reflection mirror 1705 and thus reaches a first liquidcrystal light valve 1707. On the other hand, between the blue and greenrays, the green ray is reflected by a green reflection dichroic mirror1702 and thus reaches a second liquid crystal light valve 1708. Aftertransmitted by the green reflection dichroic mirror 1702, the blue rayreaches a third liquid crystal light valve 1709. Thereafter, the firstto third liquid crystal light valves 1707, 1708 and 1709 modulatecorresponding color rays and causes the color rays to containcorresponding image information. Subsequently, the first to third liquidcrystal light valves 1707, 1708 and 1709 output the modulated colorlight. Hereat, the red light undergoing the color modulation istransmitted by the green reflection dichroic mirror 1703 and by the bluereflection dichroic mirror 1704 and then reaches a projection lens 1710(namely, the projection means). After reflected by the green reflectiondichroic mirror 1703, the green light undergoing the color modulation istransmitted by the blue reflection dichroic mirror 1704 and then reachesthe projection lens 1710. After reflected by the blue reflectiondichroic mirror 1704, the blue light undergoing the color modulationreaches the projection lens 1710.

The projection display 1700 configured in this way uses liquid crystallight valves, each of which is a light valve of the type that modulatespolarized light of a single kind. Thus, the projection display 1700 ofthis embodiment resolves substantial part of the problems of theconventional luminaire in that if randomly-polarized light is led to aliquid crystal light valve by using the conventional luminaire, half ofthe randomly-polarized light is absorbed by a polarizing plate and isconverted into heat and thus the efficiency in utilizing the light islow and in that a large cooling device which makes a great deal of noisefor controlling heat emitted from the polarizing plate is needed.

Namely, in the case of the projection display 1700 of this embodiment,the rotatory polarization is exerted only on one of the two kinds ofpolarized light (for instance, p-polarized light) by the half-wave plate446 in the polarization luminaire 400 so that the plane of polarizationthereof is made to extend in the same direction as in which the otherkind of polarized light (for example, s-polarized light). Thus, thepolarized lights, whose polarization directions are uniform, are led tothe first to third liquid crystal light valves 1707, 1708 and 1709.Consequently, the efficiency in utilizing the light can be enhanced.Moreover, a bright projected image can be obtained. Further, thequantity of light absorbed by the polarizing plate (not shown) can bereduced. Thereby, a rise in temperature of the polarizing plate can besuppressed. Consequently, it is realized that a cooling device can bemade small and its noise can be reduced. Furthermore, in thepolarization luminaire 400, a thermally stable dielectric multi-layer isused as the polarized light splitting film. The ability of the polarizedlight splitting portion 402 to split polarized light is thermallystable. The polarized light splitting portion, therefore, exerts thestable polarized light splitting ability at all times even in the caseof the projection display 1700 required to output a large quantity oflight.

Embodiment 13

FIGS. 18(A)–(B) illustrate another polarization luminaire of thisembodiment. The polarization luminaire 1800 of this embodiment isbasically provided with a light source 401, a polarized light splittingportion 402 and a system of the optical integrator 403. However, each ofthe embodiments described hereinabove employs a configuration in which aprism beam splitter composing the polarized light splitting portion isplaced at a position which is nearer to the light source than the firstlens plate of the system of the optical integrator. The luminaire ofthis embodiment, however, employs a configuration in which the prismbeam splitter composing the polarized light splitting portion is placedbetween the first lens plate and the second lens plate. Thereby, theoptical system is made to be more compact.

As shown in FIG. 18(A), randomly-polarized lights are radiated from thelight source 401 along the system optical axis L and is then incident ona deviation prism 1801 placed on the entrance side of the polarizedlight splitting portion 402. The traveling direction, in which thepolarized lights travel, is slightly inclined to the system optical axisby this deviation prism. The polarized light, therefore, is incident onthe first lens plate 441, which composes the system of the opticalintegrator 403 placed on the exit side of the deviation prism 1801, atan angle θ to the vertical incident direction. As viewed in this figure,the ray is incident thereon along a direction which is rightwardlyinclined at an angle θ to the system optical axis L.

The first lens plate 441 is optically bonded to the entrance surface1812 of a rectangular prism 1811 which is a composing element of a prismbeam splitter 1810. The half-wave plate 446 serving as the polarizationconversion element is bonded to the exit surface 1813 of the rectangularprism 1811, which is orthogonal to the entrance surface 1812 thereof.Further, the second lens plate 442 of the system of the opticalintegrator is bonded to the exit surface of this half-wave plate 446.

The prism beam splitter 1810 is provided with the rectangular prism 1811and a nearly-plate-like quadrangular prism 1820 which is bonded to theinclined surface 1813 of the prism 1811. Moreover, similarly as in thecase of the aforementioned embodiment, the polarized light splittingfilm 426 is formed on the inclined surface 1814 of the rectangular prism1811. Between the polarized lights entering, for example, only ans-polarized light is totally reflected, whereas a p-polarized light istransmitted without being changed. Furthermore, the reflection film 429is formed on the outer inclined surface 1821 of the quadrangular prism1820, so that a p-polarized light entering is totally reflected.

In the case of this embodiment, randomly-polarized lights, which hasbeen incident thereon through the deviation prism 1801 when slightlyrefracted, are reflected by the polarized light splitting film 426 andthe reflection film 429 by appropriately setting the angle formedbetween these films 426 and 429. Then, the reflected polarized lightsare further divided into polarized lights that travel on the oppositesides of the system optical axis L and are further outputted at angles,which are nearly symmetrical with respect to the system optical axis L,respectively, to the half-wave plate 446. As viewed in this figure, thereflected polarized lights are divided into polarized lights that areturned upwardly and downwardly at positive and negative angles, whichhave a same magnitude, with respect to the system optical axis L,respectively.

The half-wave plate 446 is provided with the retardation layers 447(namely, hatched portion in this figure) for turning the polarizationdirection of each of polarized lights, which pass therethrough, 90degrees, and with the layers 448 in which polarized lights passtherethrough without being changed. This configuration of the half-waveplate 446 is similar to that employed in each of the above embodiments.Between the p-polarized light and the s-polarized light that are splitin the polarized light splitting portion 402 and are turned in upwardand downward directions, which are nearly symmetrical with respect tothe system optical axis L, respectively, the s-polarized light isincident on the retardation layers 447. In contrast, the p-polarizedlight is incident on the layers 448. Thence, the polarization directionof the s-polarized light is turned 90 degrees and is thus changed into ap-polarized light which is subsequently outputted therefrom. As aresult, lights, whose polarization directions are that of thep-polarized light, are incident on the second lens plate 442.Thereafter, the lights further travel therethrough toward the region 404to be illuminated.

This embodiment using the polarization luminaire 1800 configured in thismanner can obtain effects similar to those obtained by each of theaforesaid embodiments. Further, in the configuration of this embodiment,the first and second lens plates composing the system of the opticalintegrator are formed in such a way as to be integral with each other bybeing bonded to the entrance surface and the exit surface of the prismbeam splitter, respectively. Thus, the configuration of this embodimentcan be made to be compact. Moreover, the area of the interface betweenthe optical element and the air can be reduced. Consequently, theefficiency in utilizing the light can be enhanced. Here, note that thereason for disposing the deviation prism 1801 on the optical path isthat the p-polarized light and the s-polarized light, which are obtainedby splitting a light in the aforementioned manner, are turned indirections which are symmetrical with respect to the system opticalaxis, respectively. Accordingly, the deviation prism 1801 may be placedon the exit side of the first lens plate, instead of the entrance sidethereof For example, as illustrated in FIG. 18(B), the deviation prism1801 may be bonded to the incidence entrance surface of the prism beamsplitter and moreover, the first lens plate may be bonded to theentrance surface of this deviation prism 1801. Thereby, the interfacebetween the deviation prism and the air, which is present between thefirst lens plate and the deviation prism, can be eliminated, therefore,the efficiency in utilizing the light can be more enhanced.

Furthermore, the deviation prism can be omitted by using an opticalelement composed of decentered lenses illustrated in FIG. 18(C) as thefirst lens plate.

Next, in the case of this embodiment, the number of the small lenses 444composing the second lens plate 442 may be equal to that of the smalllenses 443 composing the first lens plate 441. It is, however,preferable that the number of the small lenses 444 composing the secondlens plate 442 is twice the number of the small lenses 443 composing thefirst lens plate 441. For instance, as illustrated in FIG. 18(D), eachof the small lenses 444 of the second lens plate comprises a pair oflenses 444A and 444B respectively corresponding to the retardation layer447 and the other layer 448 of the half-wave plate 446. The reason isthat the slight difference in the optical path length between thep-polarized light and the s-polarized light, which is caused between thefirst lens plate and the second lens plate, is absorbed and the sizes ofimages of the first lens plate, which is formed by the second lens platein the region to be illuminated, is made to be uniform by changing thecharacteristics of the lenses respectively corresponding to thepolarized lights.

Embodiment 14

FIGS. 19(A)–(D) are schematic diagrams for schematically illustratingstill another polarization luminaire embodying the present invention.This embodiment uses a first condensing mirror plate and a secondcondensing mirror plate as the system of the optical integrator. Asshown in this figure, the polarization luminaire 1900 of this embodimenthas: a light source portion 401; a polarized light splitting portion402; a system of the optical integrator 403 provided with a firstcondensing mirror plate 1901 and a second condensing mirror plate 1902;and a condenser lens portion 1940, which are placed along the systemoptical axis L (L′) that makes a right-angled turn. A flux of lightsradiated from the light source portion 401 is split into fluxes of twokinds of polarized lights in the polarized light splitting portion 402.Thereafter, a flux of one kind of polarized light is synthesized againfrom the two kinds of polarized lights by the first condensing mirrorplate 1901, the second condensing mirror plate 1902 and the condenserlens portion 1940. Then, the synthesized flux of one kind of polarizedlight reaches the rectangular region 404 to be illuminated.

The light source portion 401 is mostly composed of a light source lamp411 and a paraboloidal reflector 412. Randomly-polarized lights, whichare radiated from the light source lamp 411, are reflected by theparaboloidal reflector 412 in a single direction and thus become anearly parallel luminous flux that are then incident on the polarizedlight splitting portion 402. Here, note that an ellipsoidal reflector ora spherical reflector may be used in place of the paraboloidal reflector412.

The polarized light splitting portion 402 is an ordinarysquare-pole-like beam splitters and has a configuration in which apolarized light splitting film 426 constituted by a dielectricmulti-layer film is sandwiched between the inclined surfaces of tworectangular prisms (namely, triangular prisms) made of glass. At thattime, the polarized light splitting film 426 is formed in such a way asto extend in a direction which is inclined at an angle α (=45 degrees)to the entrance surface 1911 of the polarized light splitting portion402. Incidentally, the angle α formed between the polarized lightsplitting film 426 and the entrance surface 1911 is not limited to 45degrees and may be set according to the angle of incidence of theincident fluxes of lights radiated from the light source portion 401.

A first quarter-wave plate 1921 and a second quarter-wave plate 1922 areformed on the first exit surface 1912 and the second exit surface 1923of the polarized light splitting portion 402, respectively. The firstcondensing mirror plate 1901 and the second condensing mirror plate 1902are mounted on the outer surfaces of these quarter-wave plates in suchway as to face nearly the center of the polarized light splittingportion 402. As illustrated in FIG. 19(B), these condensing mirrorplates are produced by disposing a plurality of samemicro-condensing-mirrors 1903, each of which has a rectangular outershape, in a matrix-like arrangement and forming a reflection surface1904, which is made of an ordinary aluminum evaporation film, on thesurface of each of the micro-condensing-mirrors 1903. In the case ofthis embodiment, the reflection surface 1904 of each of themicro-condensing-mirrors 1903 is shaped like a paraboloid. Incidentally,this curved reflection surface 1904 may be shaped like a spherical,elliptical or toric surface. The shape of the curved reflection surface1904 can be set according to the characteristics of the incident lightsradiated from the light source portion 401.

The condenser lens portion 1940 comprising the condenser lens plates1941 and the half-wave plate 446 is placed on the side of the region404, namely, on the third exit surface 1914 of the polarized lightsplitting portion 402 at a place, at which secondary light source imagesare formed by the first condensing mirror plate 1901 and the secondcondensing mirror plate 1902, in such a manner as to extend in adirection perpendicular to the system optical axis L, after undergoing aprocess which will be described later. The condenser lens plate 1941 isa composite lens element comprising the rectangular small lenses 1942 aspreviously described by referring to FIG. 1(B). The number of the smalllenses composing the condenser lens plate 1941 is equal to that of themicro-condensing-mirrors 1903 composing the first and second condensingmirror plates (1901 and 1902). Incidentally, in the case of thisembodiment, decentered lenses are used as a part of a plurality of thesmall lenses 1942. Further, retardation layers 447 formed in thehalf-wave plate 446 are formed in such a manner as to correspond topositions, at which secondary light source images are formed from thep-polarized light among the secondary images formed from the s-polarizedlight and the p-polarized light, with regularity.

In the polarization luminaire 1900 having such a configuration,randomly-polarized lights are radiated from the light source portion 401and are then incident on the polarized light splitting portion 402, asillustrated in FIG. 19(A). The randomly-polarized lights having beenincident on the polarized light splitting portion 402 can be consideredas mixed-lights of p-polarized lights and s-polarized lights. In thepolarized light splitting portion 402, the mixed-lights are separatedlaterally by the polarized light splitting film 426 into two kinds ofpolarized lights, namely, the p-polarized lights and the s-polarizedlights. Namely, the p-polarized light included in the randomly-polarizedlights is transmitted by the polarized light splitting film 426 withoutbeing changed, and subsequently go to the first exit surface 1912. Incontrast, the s-polarized light included in the randomly-polarizedlights is reflected by the polarized light splitting film 426, so that atraveling direction, in which the s-polarized light travels, is changedand the s-polarized light goes to the second exit surface 1913 of thepolarized light splitting portion 402.

The two kinds of polarized lights, which are obtained as a result ofsplitting by the polarized light splitting portion 402, pass through thequarter-wave plate and are then reflected by the condensing mirrorplate. During passing through the quarter-wave plate again, thedirection, in which the polarized light travels, is turned nearly 180degrees. Simultaneously with this, the plane of polarization is turned90 degrees. It will be described with reference to FIG. 19(C) how thispolarized light changes. Incidentally, for the simplicity of drawing, inthis figure, the first or second condensing mirror plate 1901 or 1902 isdrawn as a planer mirror plate 1960. The p-polarized light 1961 havingbeen incident on the quarter-wave plates 1921 and 1922 is converted bythe quarter-wave plate into a clockwise circularly polarized light(incidentally, the p-polarized light may be converted into acounterclockwise circularly polarized light, depending on the manner inwhich the quarter-wave plate is disposed). Subsequently, the circularlypolarized light reaches the mirror plate 1960. The light is thenreflected by the mirror plate 1960. Simultaneously, the direction, inwhich the plane of polarization is rotated, is also changed. Namely, aclockwise circularly polarized light is converted into acounterclockwise circularly polarized light (conversely, acounterclockwise circularly polarized light is converted into aclockwise circularly polarized light). The direction, in which the lighttravels, is turned 180 degrees by the mirror plate 1960. Simultaneously,the obtained counterclockwise circularly polarized light 1963 isconverted into the s-polarized light 1964 when passing through thequarter-wave plates 1921 and 192 again (incidentally, the obtainedclockwise circularly polarized light is converted into the p-polarizedlight). Moreover, after undergoing a similar process, the s-polarizedlight is converted into the p-polarized light.

Therefore, the p-polarized light having reached the first exit surface1912 is converted into the s-polarized light simultaneously with turningthe direction, in which the polarized light travels, nearly 180 degreesby means of the first quarter-wave plate 1921 and the first condensingmirror plate 1901. Then, the s-polarized light is reflected by thepolarized light splitting film 426 to thereby change the direction inwhich the s-polarized light travels. Thus, the s-polarized light goes tothe third exit surface 1914. On the other hand, the s-polarized lighthaving reached the second exit surface 1913 is converted into thep-polarized light simultaneously with turning the direction, in whichthe polarized light travels, nearly 180 degrees by means of the secondquarter-wave plate 1922 and the second condensing mirror plate 1902.Then, the p-polarized light is transmitted by the polarized lightsplitting film 426 without being changed. Thus, the p-polarized lightgoes to the third exit surface 1914. Namely, at that time, the polarizedlight splitting film 426 also acts as a polarized light synthesis film.

The first condensing mirror plate 1901 and the second condensing mirrorplate 1902 are composed of the micro-condensing mirrors 1903 which havelight condensing effects. Thus, simultaneously with nearly reversing thedirection in which the polarized light travels, the first condensingmirror plate 1901 and the second condensing mirror plate 1902 form aplurality of condensed images, the number of which is equal to that ofthe micro-condensing mirrors composing each of the condensing mirrorplates.

At that time, the first condensing mirror plate 1901 and the secondcondensing mirror plate 1902 are disposed in a such a manner that eachof these mirror plates is slightly tilted (namely, the first condensingmirror plate 1901 is slightly inclined at an angle β to the systemoptical axis L′, and the second condensing mirror plate 1902 is slightlyinclined at the same angle β to the system optical axis L). Thus, asecondary light source image formed from the p-polarized light andanother secondary light source image formed from the s-polarized lightare formed at positions, at which are slightly different from eachother, respectively. Namely, as illustrated in FIG. 19(D) which showssecondary light source images formed from the two kinds of polarizedlight in the case that the lens portion 1940 is viewed from the side ofthe polarized light splitting portion 402, one kind of secondary lightsource images C1 (namely, circular regions hatched with parallelslanting lines drawn from upper-left to lower-right, among circularimages) which is formed from a p-polarized light, and the other kind ofsecondary light source images C2 (namely, circular regions hatched withparallel slanting lines drawn from lower-left to upper-right, among thecircular images), which is formed from an s-polarized light, are formedside by side. In contrast with this, in the half-wave plate 446, theretardation layer 447 is selectively formed correspondingly to aposition where the secondary light source image C1 is formed from thes-polarized light (incidentally, the p-polarized light radiated from thelight source portion is converted into the s-polarized light byperforming the process illustrated in FIG. 19(C) and this s-polarizedlight is incident on the half-wave plate 446). Thus, when passingthrough the retardation layer 447, the p-polarized light undergoes arotatory polarization, so that the p-polarized light is converted intos-polarized light. On the other hand, the s-polarized light does notpass through the retardation layer 447 and thus passes through thehalf-wave plate 446 without undergoing the rotatory polarization.Consequently, most of the luminous fluxes radiated from the condenserlens portion 1940 are made to be p-polarized lights.

The fluxes of lights, which have been made to be p-polarized light, areapplied to the region 404 to be illuminated. Namely, images of imageplanes extracted by the first condensing mirror plate 1901 and themicro-condensing-mirrors 1903 of the second condensing mirror plate 1902are formed at a single place by the condenser lens plate 1941 in such amanner as to be superposed thereon. Further, when passing through thehalf-wave plate 446, the lights are converted into polarized lights of asingle kind. Thus most of the lights reach the region 404 to beilluminated. Consequently, the region 404 to be illuminated is uniformlyilluminated with the polarized lights, most of which are of the singlekind.

As above described, in the case of the polarization luminaire 1900 ofthis embodiment, a randomly-polarized light radiated from the lightsource portion 401 is split by the polarized light splitting portion 402into two kinds of polarized lights which travel in different directions.Thereafter, each of the two kinds of polarized lights is led to apredetermined region of the half-wave plate 446, whereupon ans-polarized light is converted into a p-polarized light. Thus, therandomly-polarized lights radiated from the light source portion 401 canbe applied to the region to be illuminated, while most of the polarizedlights are in a state in which they are made to be p-polarized lights.

Moreover, high ability of the polarized light splitting portion 402 tosplit polarized light is necessary for leading each of the two kinds ofpolarized lights to the predetermined region of the half-wave plate 446.In the case of this embodiment, the polarized light splitting portion402 is constituted by utilizing the prisms made of glass and thedielectric multi-layer film made of an inorganic material. Thus, thepolarized light splitting ability of the polarized light splittingportion 402 is thermally stable. The polarized light splitting portion402, therefore, exerts the stable polarized light splitting ability atall times even in the case that the luminaire is required to output alarge quantity of light. Consequently, the polarization luminaire havingsatisfactory ability can be realized.

Further, in the case of this embodiment, in accordance with the shape ofthe region 404 to be illuminated, which is a laterally elongatedrectangle, the micro-condensing-mirrors 1903 of the first condensingmirror 1901 and the second condensing mirror 1902 are in the shape of alaterally elongated rectangle. The two kinds of polarized lightssimultaneously radiated from the polarized light splitting portion 402are separated in the transverse direction. Thus, even in the case thatthe illumination region 404 to be illuminated, whose shape is alaterally elongated rectangle, is formed, the illumination efficiencycan be increased without wasting a quantity of light.

In the case of Embodiment 14, the half-wave plate 446 is placed to theillumination region side of the condenser lens plate 1941. However, theposition, at which the half-wave plate 446 is placed, is not limitedthereto. The half-wave plate 446 may be placed at another position aslong as this position is in the vicinity of a position where a secondarylight source image is formed. For example, the half-wave plate 446 isplaced to the light source side of the condenser lens plate 1941.

Further, each of the small lenses 1942 composing the condenser lensplate 1941 is a laterally-elongated rectangular lens. In contrast, thereis no limitation to the shape of each of the small lenses 1942 of thecondenser lens plate 1941. Incidentally, because the secondary lightsource image C1, which is formed from the p-polarized light, and thesecondary light source image C2, which is formed from the s-polarizedlight, are formed side by side in the transverse direction asillustrated in FIG. 1 9(D), it is preferable that the shape of each ofthe small lenses 1942 of the condenser lens plate 1941 is determined,correspondingly to the positions where such images are formed.

Moreover, the two retardation layers, which have differentcharacteristics, may be placed at a position, at which p-polarized lightis condensed, and at another position, at which s-polarized light iscondensed, respectively. Furthermore, the lights may be made to bepolarized lights of a single kind that have a specific polarizationdirection.

Embodiment 15

In the case of Embodiment 14, it is necessary for spatially separating aposition, at which a secondary light source image is formed from thep-polarized light, from a position, at which a secondary light sourceimage is formed from the s-polarized light, to dispose the firstcondensing mirror plate 1901 and the condensing mirror plate 1902 in astate in which each of these plates is slightly tilted (namely, thefirst condensing mirror plate 1901 is slightly inclined at an angle β tothe system optical axis L′, and the second condensing mirror plate 1902is slightly inclined at the same angle β to the system optical axis L).However, one or both of the condensing mirror plates can be disposed ina direction perpendicular to the system optical axis L (or L′) by usinga deviation prism. As will be described later, if such a perpendicularplacement thereof is realized, the condensing mirror plates can beformed in such a way as to be integral with the polarized lightsplitting portion 402 or the quarter-wave plate 1921 (or thequarter-wave plate 1922).

A polarization luminaire 2000 of Embodiment 15 illustrated in FIG. 20 isrealized by taking this respect into consideration. The basisconfiguration of this polarization luminaire 2000 is similar to that ofthe polarization luminaire 1900 of Embodiment 14. Same referencecharacters designate same parts having the same functions. Further, thedescriptions of such parts are omitted herein.

In the polarization luminaire 2000, a deviation prism 2001 is placedbetween the light source portion 401 and the polarized light splittingportion 402. The first condensing mirror plate 1901 can be placed in aposition perpendicular to the system optical axis L′ by disposing thedeviation prism 2001 at this place. Thereby, the production of theoptical system can be facilitated. Needless to say, if the deviationprism 2001 is reversed (namely, the deviation prism illustrated in FIG.20 is disposed in such a manner that the acute-angled portion thereoffaces the second condensing mirror plate 1902), the second condensingmirror plate 1902 can be placed in a position perpendicular to thesystem optical axis L, instead of the first condensing mirror plate1901.

Moreover, the deviation prism 2001 can be formed in such a way as to beintegral with the polarized light splitting portion 402. In such a case,this embodiment have an advantage in that the loss of the light due tothe reflection caused on the interface between the deviation prism 2001and the entrance surface 1911 of the polarized light splitting portion402 can be further reduced.

Embodiment 16

It has been described that in the case of Embodiment 15, the firstcondensing mirror plate 1901 can be placed in a position perpendicularto the system optical axis L′ (alternatively, the second condensingmirror plate 1902 can be placed in a position perpendicular to thesystem optical axis L) by disposing the deviation prism 2001 between thelight source portion 401 and the polarized light splitting portion 402and that thereby, the integration of the first condensing mirror plate1901, the polarized light splitting portion 402 and the quarter-waveplate into a single piece become easy. A practical example isillustrated in FIGS. 21(A)–(B) as a polarization luminaire 2100, namely,as Embodiment 16.

In the case of this embodiment, a condensing mirror plate 2101, whoseexternal view is illustrated in FIG. 21(B), is used. Namely, theentrance surface 2102 thereof is planar and a curved-surface-likereflection surface 2104 thereof is formed on the rear surface of a block2103 made of glass. As illustrated in FIG. 21(A), the exit surface ofthe polarized light splitting portion 402 (in this case, the first exitsurface 1912), the quarter-wave plate (in this case, the firstquarter-wave plate 1921) and the condensing mirror plate 2101(corresponding to the first condensing mirror plate in this case) can beformed by employing such a shape of the condensing mirror plate 2101 insuch a manner as to be integral with one another. Thus, this embodimentshas advantages in that the optical system can be made to be more compactand that furthermore, the loss due to the optical reflection on theinterface can be reduced.

Embodiment 17

Further, as illustrated in FIG. 22, in a polarization luminaire 2200,deviation prisms 2001 are placed at two places, namely, placed in thefirst condensing mirror plate 1901 and the second condensing mirror1902. In this case, both of the first condensing mirror plate 1901 andthe second condensing mirror 1902 can be disposed in positionsperpendicular to the system optical axis L′ (or the system optical axisL). Thereby, the placement of the condensing mirror plates can befacilitated.

Incidentally, in the case of this embodiment, the deviation prism 2001is optically bonded to the first exit surface 1912 and the second exitsurface 1913 of the polarized light splitting portion 402 and is thusformed in such a manner as to be integral therewith. Consequently, thisembodiment has an advantage in that the loss due to the opticalreflection on the interface can be reduced.

Further, the first quarter-wave plate 1921 (or the second quarter-waveplate 1922) may be placed between the first exit surface 1912 (or thesecond exit surface 1913) of the polarized light splitting portion 402and the deviation prism 2001.

Embodiment 18

The deviation prisms 2001 disposed in two places in Embodiment 17 may beplaced in such a manner as to be integral with the first condensingmirror plate 1901 and the second condensing mirror plate 1902,respectively. In such a case, this embodiment has an advantage in thatthe loss due to the optical reflection on the interface can be reduced.An example of the configuration in such a case is illustrated in FIG. 23as a polarization luminaire 2300, namely, Embodiment 18. In the case ofthis embodiment, the condensing mirror plates 2101 similar to thoseemployed in Embodiment 16 are used to form the deviation prism 2001 andthe first condensing mirror plate 1901 in such a manner as to beintegral with each other, and to form the deviation prism 2001 and thesecond condensing mirror plate 1902 in such a manner as to be integralwith each other, respectively.

Furthermore, the first quarter-wave plate 1921 (or the secondquarter-wave plate 1922) may be placed between the first condensingmirror plate 2101 (or the second condensing mirror plate 2102) and thedeviation prism 2001.

Embodiment 19

Moreover, as illustrated in FIG. 24, in a polarization luminaire 2400,the combination of the polarized light splitting portion 402, the firstquarter-wave plate 1921, the deviation prism 2001 and the firstcondensing mirror plate 2101 and the combination of the polarized lightsplitting portion 402, the second quarter-wave plate 1922, the deviationprism 2001 and the second condensing mirror plate 2102 can be formed insuch a way as to be integral with each other. In such a case, thisembodiment has an advantage in that the loss due to the opticalreflection on the interface can be reduced. Incidentally, in the case ofthis embodiment, the condensing mirror plates 2101 similar to thoseemployed in Embodiment 16 previously described are used.

Furthermore, the first quarter-wave plate 1921 (or the secondquarter-wave plate 1922) may be placed between the first condensingmirror plate 2101 (or the second condensing mirror plate 2102) and thedeviation prism 2001.

Embodiment 20

In the case of a polarization luminaire 2500 illustrated in FIG. 25, theplacement of each optical system is similar to that of each of theoptical systems of Embodiment 14. However, Embodiment 20 has thefollowing characteristic features. Namely, the prism structure element402 is constituted by six transparent plates 2501 composing wallsurfaces. Further, in a planar polarized light splitting plate 2502, inwhich the polarized light splitting film 426 is formed, is disposedtherein. Moreover, a structure element filled with liquid 2503 is usedas the polarized light splitting portion 402. Thereby, the cost andweight of the polarized light splitting portion 402 can be reduced.

Embodiment 21

In the case of a polarization luminaire 2600 illustrated in FIG. 26, theplacement of each optical system is similar to that of each of theoptical systems of Embodiment 14. However, Embodiment 21 has acharacteristic feature in that the polarized light splitting portion 402is a planar structure element. Namely, the polarized light splittingplate 2502, in which the polarized light splitting film 426 is formed,is disposed in such a manner as to be inclined at an angle γ (=45degrees) to the system optical axis L′. Thereby, the polarized lightsplitting portion 402 of this embodiment can exert the functions thatare substantially the same as of the polarized light splitting portion402 illustrated in FIG. 14 mainly comprising two rectangular prisms.Consequently, the cost and weight of the polarized light splittingportion 402 can be reduced.

Example of Protection Display Using Polarization Luminaire of Embodiment14

FIG. 27 illustrates an example of the projection display which increasesthe brightness of an image by using the polarization luminaire ofEmbodiment 14, among those of Embodiment 14 to Embodiment 21.

As shown in FIG. 27, a projection display 2700 of this example isprovided with the light source portion 401 for radiatingrandomly-polarized lights in a single direction. In the polarized lightsplitting portion 402, a randomly-polarized light radiated from thislight source portion 401 is separated into two kinds of polarizedlights. Between the two kinds of polarized lights, an s-polarized lightis converted by the half-wave plate 446 of the condenser lens portion1940 into a p-polarized light.

Among a flux of lights radiated from such a polarization luminaire 1900,red rays are transmitted by and blue and green rays are reflected by theblue-and-green reflection dichroic mirror 2701. Then, the red rays arereflected by a reflection mirror 2702 and thus reaches a first liquidcrystal light valve 2703. On the other hand, between the blue and greenrays, the green rays are reflected by a green reflection dichroic mirror2704 and thus reaches a second liquid crystal light valve 2705.

Here, note that blue light has optical path length longer than that ofthe other two colors (incidentally, the optical path length of red lightis equal to that of green light). Thus, a light guiding means 2750constituted by a relay lens system comprising an entrance side lens2706, a relay lens 2708 and an exit side lens 2710 is provided for bluerays. Namely, after transmitted by a green reflection dichroic mirror2704, the blue light is first led to the relay lens 2708 through thelens 2706 and by way of a reflection mirror 2707. Then, after convergedinto this relay lens 2708, the blue light is led to the exit side lens2710 by way of a reflection mirror 2709. Thereafter, the blue lightreaches a third liquid crystal light valve 2711. Hereat, the first tothird liquid crystal light valves 2703, 2705 and 2711 modulatecorresponding color rays. Subsequently, the modulated color rays aremade to be incident on a dichroic prism (namely, a color synthesismeans) 2713. The dichroic prism 2713 has a red reflection dielectricmulti-layer film and a blue reflection dielectric multi-layer film thatare arranged crosswise therein and synthesize bundles of modulated raysof such colors, respectively. The bundles of rays synthesized thereinpass through a projection lens 2714 (namely, a projection means) andcome to form images on a screen 2715.

The projection display 2700 configured in this way uses liquid crystallight valves, each of which is a light valve of the type that modulatespolarized light of a single kind. Thus, the projection display 2700 ofthis embodiment resolves substantial part of the problems of aconventional luminaire in that if randomly-polarized light is led to aliquid crystal light valve by using the conventional luminaire, half ofthe randomly-polarized light is absorbed by a polarizing plate and isconverted into heat and thus the efficiency in utilizing the light islow and in that a large cooling device which makes a great deal of noisefor controlling heat emitted from the polarizing plate is needed.

Namely, in the case of the projection display 2700 of this embodiment,the rotatory polarization is exerted only on one of the two kinds ofpolarized light (for instance, s-polarized light) by the half-wave plate446 in the polarization luminaire 1900 so that the plane of polarizationthereof is made to extend in the same direction as in which the otherkind of polarized light. Thus, the polarized lights, whose polarizationdirections are uniform, are led to the first to third liquid crystallight valves 2703, 2705 and 2711. Consequently, the efficiency inutilizing the light can be enhanced. Moreover, a bright projected imagecan be obtained. Further, the quantity of light absorbed by thepolarizing plate (not shown) can be reduced. Thereby, a rise intemperature of the polarizing plate can be suppressed. Consequently, itis realized that a cooling device can be made small and its noise can bereduced. Furthermore, in the polarization luminaire 1900, a thermallystable dielectric multi-layer is used as the polarized light splittingfilm. The ability of the polarized light splitting portion 402 to splitpolarized light is thermally stable. The polarized light splittingportion, therefore, exerts the stable polarized light splitting abilityat all times even in the case of the projection display 2700 required tooutput a large quantity of light.

Besides, in the polarization luminaire 1900, the two kinds of polarizedlights radiated from the polarized light splitting portion 402 areseparated in the transverse direction. Thus, the region to beilluminated, whose shape is a laterally elongated rectangle, can beformed without wasting any quantity of light. Consequently, thepolarization luminaire 1900 is suitable for a laterally-elongated liquidcrystal light valve which can project an image which is easy to see andappeals strongly.

In addition, this embodiment uses a dichroic prism 2713 as the colorsynthesis means. Thus, the size of the device can be reduced. Moreover,the length of the optical path between the projection lens 2714 and eachof the liquid crystal light valves 2703, 2705 and 2711 is short. Thus,in the case of the device of this embodiment, a bright projected imagecan be realized even if a projection lens having a relatively smalldiameter is used. Further, in the case of this embodiment, the lightguiding means 2750 constituted by the relay lens system consisting ofthe entrance side lens 2706, the relay lens 2708 and the exit side lens2710 is provided for blue rays. Consequently, irregularities in colorsor the like do not occur in projected images.

Incidentally, needless to say, the luminaire of another embodiment maybe used instead of the luminaire 1900.

In the projection display, the color synthesis means may be constitutedby an optical system using mirrors as illustrated in FIG. 28. In thecase that an optical system using mirrors is used in the color synthesismeans, the three liquid crystal light valves 2703, 2705 and 2711 and thelight source portion 401 have the same optical path length. Thus, theprojection display is characterized in that even if no special lightguiding means is used, this display device can achieve effectiveillumination, by which irregularities in brightness and color hardlyoccur in images.

Namely, a projection display 2800 illustrated in FIG. 28 employs thepolarization luminaire 1900 illustrated in FIGS. 19(A)–(D). In thepolarized light splitting portion 402, a randomly-polarized lightradiated from this light source portion 401 is separated into two kindsof polarized lights. Between the two kinds of polarized lights, ans-polarized light is converted by the half-wave plate 446 of thecondenser lens portion 1940 into a p-polarized light.

Among a flux of lights radiated from such a polarization luminaire 1900,first, red rays are reflected by and blue and green rays are transmittedby a red reflection dichroic mirror 2801. Then, the red rays arereflected by a reflection mirror 2802 and thus reach a first liquidcrystal light valve 2703. On the other hand, between the blue and greenrays, the green rays are reflected by a green reflection dichroic mirror2803 and thus reach a second liquid crystal light valve 2705. Aftertransmitted by the green reflection dichroic mirror 2804, the blue raysreach a third liquid crystal light valve 2711. Thereafter, the first tothird liquid crystal light valves 2703, 2705 and 2711 modulatecorresponding color rays and causes the color rays to containcorresponding image information. Subsequently, the first to third liquidcrystal light valves 1707, 1708 and 1709 output the modulated colorrays. Hereat, the red rays undergoing the color modulation istransmitted by the green reflection dichroic mirror 2804 and by the bluereflection dichroic mirror 2805 and then reach a projection lens 2714(namely, the projection means). After reflected by the green reflectiondichroic mirror 2804, the green rays undergoing the intensity modulationis transmitted by the blue reflection dichroic mirror 2805 and thenreach the projection lens 2714. After reflected by the blue reflectiondichroic mirror 2805, the blue rays undergoing the intensity modulationreach the projection lens 2714.

The projection display 2800, in which the color synthesis means isconstituted by the optical system using mirrors comprising the dichroicmirrors in this way, uses liquid crystal light valves, each of which isa light valve of the type that modulates polarized light of a singlekind. Thus, the projection display 2800 of this embodiment resolvessubstantial part of the problems of the conventional luminaire in thatif randomly-polarized light is led to a liquid crystal light valve byusing the conventional luminaire, half of the randomly-polarized lightis absorbed by a polarizing plate and is converted into heat and thusthe efficiency in utilizing the light is low and in that a large coolingdevice which makes a great deal of noise for controlling heat emittedfrom the polarizing plate is needed.

Namely, in the case of the projection display 2800 of this embodiment,the rotatory polarization is exerted only on one of the two kinds ofpolarized light (for instance, s-polarized light) by the half-wave plate446 in the polarization luminaire 1900 so that the plane of polarizationthereof is made to extend in the same direction as in which the otherkind of polarized light (for example, p-polarized light). Thus, thepolarized lights, whose polarization directions are uniform, are led tothe first to third liquid crystal light valves 2703, 2705 and 2711.Consequently, the efficiency in utilizing the light can be enhanced.Moreover, a bright projected image can be obtained. Further, thequantity of light absorbed by the polarizing plate (not shown) can bereduced. Thereby, a rise in temperature of the polarizing plate can besuppressed. Consequently, it is realized that a cooling device can bemade small and its noise can be reduced. Furthermore, in thepolarization luminaire 1900, a thermally stable dielectric multi-layerfilm is used as the polarized light splitting film. The ability of thepolarized light splitting portion 402 to split polarized light isthermally stable. The polarized light splitting portion, therefore,exerts the stable polarized light splitting ability at all times even inthe case of the projection display 2800 required to output a largequantity of light.

Embodiment 22

FIGS. 29(A)–(B) illustrate yet another example of the polarizationluminaire of the present invention. The polarization luminaire 2900 ofthis embodiment is mostly composed of a light source portion 401, afirst lens plate 441 and a second lens plate 2901, which are placedalong the system optical axis L. A flux of lights radiated from thelight source portion 401 are converged by the first lens plate 441 andthen reach to the second lens plate 2901. During passing through thesecond lens plate 2901, the randomly-polarized lights are converted intopolarized lights of a single kind, whose polarization directions areuniform. Then, the polarized lights of this single kind reach therectangular region 404 to be illuminated.

The light source portion 401 is mostly composed of a light source lamp411 and a paraboloidal reflector 412. Randomly-polarized lights, whichare radiated from the light source lamp 411, are reflected by theparaboloidal reflector 412 in a single direction and thus become anearly parallel luminous flux that is then incident on the first lensplate 441. Here, note that an ellipsoidal reflector or a sphericalreflector may be used in place of the paraboloidal reflector 412.

The first lens plate 441 comprises a plurality of small condensinglenses 443 disposed therein, each of which has a rectangular outsideshape. Convergent light images, the number of which is equal to that ofthe small condensing lenses 443, are formed from flux of lights which isincident on the first lens plate 441, in a plane which is perpendicularto the system optical axis L, by the condensing action of the smallcondensing lenses 443. The plurality of convergent light images arenothing else but projected images of the light source lamp. Thus,hereunder, the convergent light images will be referred to as secondarylight source images.

The second lens plate 2901 of this embodiment is different from thesecond lens plate of each of the aforementioned embodiments and is acomposite layered element comprising a condenser lens array 2902, apolarized light splitting prism array 2903, a half-wave plate 2904 andan exit side lens 2905. The second lens plate 2901 of this embodiment isplaced in a plane, which is perpendicular to the system optical axis L,in the vicinity of a place at which a secondary light source image isformed by the first lens plate 441. This second lens plate 2901 has thefunctions as of the second lens plate of the system of the opticalintegrator, as of the polarized light splitting element and as of thepolarized light conversion element.

The condenser lens array 2902 has a configuration similar to that of thefirst lens plate 441. Namely, the condenser lens array 2902 comprises aplurality of condenser lenses 2910 disposed therein, the number of whichis equal to that of the micro-condensing-lenses composing the first lensplate 441. The condenser lens array 2902 is operative to condense lightoutputted from the first lens plate 441. Here, note that each of thesmall condensing lenses 443 composing the first lens plate 441 does notnecessarily have the same size, shape and lens characteristics as ofeach of the condenser lenses 2910 composing the condenser lens array2902. It is preferable that each of the small condensing lenses 443 andthe condenser lenses 2910 is optimized according to the characteristicsof light emitted from the light source portion 401. It is, however,ideal that the principal one of rays entering the polarized light prismarray 2903 is parallel with the system optical axis L. From this pointof view, it is frequent that a lens having the same lens characteristicsas of the small condensing lens 443 of the first lens plate 441 or alens, which has a shape similar to that of the small condensing lens 443and the same lens characteristics as of the micro-condensing-lens 443,is employed as the condenser lens 2910. Thus, the condenser lens array2902 corresponds to the second lens plate of the system of the opticalintegrator.

The polarized light splitting prism array 2903, whose external view isillustrated in FIG. 29(B), has a pair of a square-pole-like polarizingbeam splitter 2921 and a square-pole-like reflection mirror 2922 as afundamental composing element. A plurality of such pairs are disposed ina plane (in which secondary light source images are formed) in thepolarized light splitting prism array 2903 with regularity in such amanner that a pair of fundamental composing elements correspond to thecondenser lens 2910 of the condenser lens array 2902. Further, the widthWp of one of the polarizing beam splitters 2921 is equal to the width Wmof one of the reflection mirrors 2922.

Moreover, Wp and Wm are set at half of the width of one of the condenserlenses 2910 composing the condenser lens array 2902.

Here, the second lens plate 2901 including the polarized light prismarray 2903 is placed in such a way that secondary light source imagesare formed in the polarizing beam splitter 2921 by the first lens plate441. Thus, the light source portion 401 is disposed in such a mannerthat the light source optical axis R thereof is slightly inclined at asmall angle.

Randomly-polarized light having been incident on the polarized lightprism array 2921 is separated by the polarizing beam splitter 2921 intotwo kinds of polarized lights having different polarization directions,namely, the p-polarized lights and the s-polarized lights. Namely, thep-polarized light passes through the polarizing beam splitter withoutchanging the traveling direction thereof. In contrast, the s-polarizedlight is reflected on the polarized light splitting surface 2931 of thepolarizing beam splitter 2921, so that the traveling direction, in whichthe s-polarized light travels, is turned about 90 degrees. Then, thes-polarized light is reflected again on the reflection surface 2941 ofthe adjacent reflection mirror 2922 (of the pair), so that the travelingdirection, in which the s-polarized light travels, is turned about 90degrees. Finally, the s-polarized light goes out from the polarizedlight splitting prism array 2903 in such a manner as to be nearly inparallel with the p-polarized light.

The half-wave plate 2904, in which λ/2 retardation films 2951 are placedwith regularity, is disposed on the exit surface of the polarized lightsplitting prism array 2903. Namely, the λ/2 retardation films 2951 areplaced only in the exit surface portions of the polarizing beamsplitters 2921 composing the polarized light splitting prism array 2903.However, the λ/2 retardation films 2951 are not placed in the exitsurface portion of the reflection mirrors 2922. With such placement ofthe λ/2 retardation film 2951, the p-polarized light radiated from thepolarizing beam splitter 2921 undergoes a rotatory polarization whenpassing through the λ/2 retardation film 2951, so that the p-polarizedlight is converted into s-polarized light. On the other hand, thes-polarized light reflected from the reflection mirror 2922 does notpass through the λ/2 retardation film 2951 and thus passes through thehalf-wave plate 2904 without undergoing the rotatory polarization. Insummary, randomly-polarized light are converted by the polarized lightsplitting prism array 2903 and the half-wave plate 2904 into polarizedlight of a single kind (in this case, s-polarized light).

The flux of lights, which have been made to be s-polarized light, areled by the exit side lens 2905 to the region 404 to be illuminated.Further, images are formed from the s-polarized light and are superposedon the region 404 to be illuminated. Namely, images of image planesextracted by the first lens plate 441 are formed by the second lensplate 2901 in such a manner as to be superposed thereon. Simultaneously,the randomly-polarized light is spatially separated by the polarizedlight splitting prism array 2903 placed at a midpoint into two kinds ofpolarized lights. When passing through the half-wave plate 2904, thelights are converted into polarized lights of a single kind. Thus mostof the lights reach the region 404 to be illuminated. Consequently, theregion 404 to be illuminated is almost uniformly illuminated with thepolarized lights, most of which are of the single kind.

As above described, in the case of the polarization luminaire 2900 ofthis embodiment, a randomly-polarized light radiated from the lightsource portion 401 is converged by the first lens plate 441 intopredetermined micro-regions of the-polarized light splitting prism array2903 and is then spatially separated into two kinds of polarized lights,whose polarization directions are different from each other. Thereafter,each of the two kinds of polarized lights is led to a predeterminedregion of the half-wave plate 2904, whereupon a p-polarized light isconverted into an s-polarized light. Thus, this embodiment exerts theeffects in that the randomly-polarized lights radiated from the lightsource portion 401 can be applied to the region 404 to be illuminated,while most of the polarized lights are in a state in which these beamsare made to be s-polarized lights. Moreover, in the process ofconverting the polarized light, the loss of light hardly occurs.Consequently, this embodiment has a characteristic feature in that theefficiency in utilizing light outputted from the light source isextremely high.

Further, in the case of this embodiment, in accordance with the shape ofthe region 404 to be illuminated, which is a laterally elongatedrectangle, the micro-condensing-mirrors 443 of the first lens plate 441are in the shape of a laterally elongated rectangle. Simultaneously, thetwo kinds of polarized lights radiated from the polarized light prismarray 2903 are separated in the transverse direction. Thus, even in thecase that the illumination region 404 to be illuminated, whose shape isa laterally elongated rectangle, is formed, the illumination efficiencycan be increased without wasting a quantity of light.

Embodiment 23

In the case of Embodiment 22, the second lens plate 2901 including thepolarized light prism array 2903 is placed in such a way that secondarylight source images formed by the first lens plate 441 are placed in thepolarizing beam splitter 2921. Thus, the light source portion 401 isrequired to be disposed in such a manner that the light source opticalaxis R thereof is slightly inclined at a small angle. However, the lightsource optical axis R can be made to coincide with the system opticalaxis L by providing the deviation prism in the luminaire. Consequently,the light source portion can be disposed therein without being inclined.

Namely, the luminaire of the present invention may be configured as apolarization luminaire 3000 of Embodiment 23 illustrated in FIG. 30. Inthe case of the polarization luminaire 3000 of Embodiment 23 illustratedin FIG. 30, a deviation prism 3001 is placed between the light source401 and the first lens plate 441. When a ray radiated from the lightsource portion 401 is incident on the deviation prism 3001, thetraveling direction, in which the ray travels, is slightly turned by thedeviation prism. Thus, the ray is then incident on the first lens plate441 at an angle which is not a right angle. Thereafter, the ray reachesa predetermined position in the polarizing beam splitter 2921.

Namely, a place, at which a secondary image is formed by the first lensplate 441, can be arbitrarily set by providing the deviation prism 3001.Thus, the light source portion 401 can be disposed on the system opticalaxis L. Consequently, the optical system can be produced simply andeasily.

Furthermore, the deviation prism 3001 can be formed in such a way as tobe integral with the first lens plate 441. In such a case, the number ofthe interfaces between the deviation prism and the first lens plate 441can be decreased. Consequently, light radiated from the light source 401can be led to the second lens plate 2901 without any loss of the light.

Embodiment 24

The placement of the light source portion 401 on the system optical axisL can be realized by a method of using a decentered lens as themicro-condensing-lenses composing the first lens plate 441, other thanthe method employed in Embodiment 23 which has been previouslydescribed. A practical example of this is illustrated in FIG. 31 as thepolarization luminaire 3100, namely, Embodiment 24.

As illustrated in FIG. 31, in the case of the luminaire 3100 of thisembodiment, the first lens plate 441 is constituted by the decenteredmicro-condensing-lenses 3101. The principal ray of a flux of lightsradiated from the first lens plate 441 is slightly inclined in such amanner that a secondary light source image is formed at a predeterminedplace in the polarizing beam splitter 2921. Thus, the light sourceportion 401 can be placed on the system optical axis L. Consequently,the manufacture of optical systems can be simplified and facilitated.

Embodiment 25

Any of the second lens plates 2901 used in the aforementioned Embodiment22 to Embodiment 24 has the condenser lens array 2902 and the exit sidelens 2905. As to rays entering the polarized light prism array 2903, itis ideal that the principal ray is parallel to the system optical axisL. Most of the condenser lens arrays 2902 are constituted by usinglenses that are the same as the micro-condensing-lenses 443 composingthe first lens plate 441. Further, the exit side lens 2905 is necessaryfor forming an image on the predetermined illumination region 404 from aflux of lights passing through different positions on the second lensplate 2901, which are away from the system optical axis L, in such a wayas to be superposed thereon.

The exit side lens 2905, however, can be omitted by using a decenteredlens as the condenser lens array 2902 and by regulating an installationangle of the reflection surface 2941 of the reflection mirror 2922. Apractical example is illustrated in FIG. 32 as a polarization luminaireof Embodiment 25.

As shown in FIG. 32, the condenser lens array 2902 is constructed byusing the decentered condenser lens 3201. Thus, in the condenser lensarray 2902, the principal ray of the p-polarized light passing throughthe polarizing beam splitter 2921 can be directed to the center 404 a ofthe region to be illuminated. This embodiment can deal with bundles ofrays passing through the polarizing beam splitter 2921, which are placedaway from the system optical axis L, by increasing the amount ofeccentricity of the decentered condenser lens 3201.

On the other hand, the principal ray of the s-polarized lights, whichgoes out through the polarizing beam splitter 2921 and the reflectionmirror 2922, can be directed to the center 404 a of the illuminationregion by setting the installation angle of the reflection surface 2941of the reflection mirror 2922 at a suitable value. Needless to say, inthis case, it is necessary to individually optimize the installationangle of the reflection surface according to the distance thereof fromthe system optical axis L.

With the aforementioned configuration, the exit side lens 2905 becomesunnecessary. Thus, the cost of the optical system can be reduced.

Further, in the case of employing a configuration which does not use anexit side lens similarly as in the case of this embodiment, the place atwhich the condenser lens array 2902 is not limited to the light sourceside of the polarized light splitting prism array 2903. Moreover, thecondenser lens array 2902 can be placed on the region-to-be-illuminatedside of the polarized light splitting prism array 2903, in the case ofemploying some lens characteristics of the decentered condenser lenses3201 composing the condenser lens array 2902 and some installationangles of the polarized light splitting surface 2931 and the reflectionangle 2941 of the polarized light splitting prism array 2903.

Embodiment 26

In any of the aforementioned Embodiment 22 to Embodiment 25, the lightsource portion 401 and the first lens plate 441 are placed on the systemoptical axis L. Secondary light source images are formed atpredetermined positions in the polarizing beam splitter 2921 byregulating the orientation of the light source portion 401 or the lenscharacteristics of the first lens plate 441. In contrast, if shiftingboth of the light source portion 401 and the first lens plate 441 inparallel with the system optical axis, similar advantages can beobtained.

Moreover, turning attention to the lateral size (namely, the width) ofeach of the condenser lenses 2910 composing the condenser lens array2902 of the second lens plate 2901, as is understood from the fact thatsecondary light source images are always formed only on the polarizingbeam splitter 2921, the condenser lens 2910 satisfactorily functions ifthe width thereof is equal to the width Wp of the polarizing beamsplitter 2921.

A practical example of this is illustrated in FIG. 33 as thepolarization luminaire 3300 of Embodiment 26. In the case of thisembodiment, the light source portion 401 and the first lens plate 441are placed by being shifted in parallel with each other with respect tothe system optical axis L in the direction (namely, the downwarddirection as viewed in this figure), in which the polarizing beamsplitter 2921 is provided in the polarized light splitting prism array2903, by a shifted distance (=D) corresponding to a half of the width Wpof the polarizing beam splitter 43. Furthermore, the condenser lensarray 2902 of the second lens plate 2901 is constructed by using andplacing condensing semi-transparent lenses 3301, each of which has alens width (namely, a lateral width) equal to the width Wp of thepolarizing beam splitter 292, correspondingly to the places at which thepolarizing beam splitter is mounted.

With the aforementioned configuration, the designing of the opticalsystem can be facilitated. Further, the cost of the optical system canbe reduced.

Projection Display Using Luminaire of Embodiment 24

FIG. 34 illustrates an example of a projection display using thepolarization luminaire 3100 illustrated in FIG. 31, among the luminariesof Embodiment 23 to Embodiment 26.

As shown in FIG. 34, the light source portion 401 for radiatingrandomly-polarized light in a single direction is provided in thepolarization luminaire 3100 of a device 3400 of this embodiment. Arandomly-polarized light, which is radiated from this light sourceportion 401 and is condensed by the first lens plate 441, is led to apredetermined position in the second lens plate 2901. Thereafter, therandomly-polarized light is separated by the polarized light prism array2903 of he second lens plate 2901 into two kinds of polarized lights.Between the two kinds of polarized lights, a p-polarized light isconverted by the half-wave plate 2904 into an s-polarized light.

Among flux of lights radiated from this polarization luminaire 3100,first, a red rays are reflected by and blue and green rays aretransmitted by a blue-and-green reflection dichroic mirror 3401. The redrays are reflected by a reflection mirror 3402 and subsequently, reach afirst liquid crystal light valve 3403. On the other hand, between theblue and green rays, the green rays are reflected by a green reflectiondichroic mirror 3404 and thus reach a second liquid crystal light valve3405.

Here, note that blue rays have optical path length longer than that ofany other two color rays. Thus, a light guiding means (light guide) 3450constituted by a relay lens system comprising an entrance side lens3406, a relay lens 3408 and an exit side lens 3410 is provided for bluerays. Namely, after transmitted by a green reflection dichroic mirror3404, the blue rays are first led to the relay lens 3408 through thelens 3406 and by way of a reflection mirror 3407. Then, after convergedinto this relay lens 3408, the blue rays are led to the exit side lens3410 by way of a reflection mirror 3409. Thereafter, the blue rays reacha third liquid crystal light valve 3411. Hereat, the first to thirdliquid crystal light valves 3403, 3405 and 3411 modulate correspondingcolor rays and cause the color rays to contain corresponding imageinformation. Subsequently, the modulated color rays are made to beincident on a dichroic prism (namely, a color synthesis means) 3413. Thedichroic prism 3413 has a red reflection dielectric multi-layer film anda blue reflection dielectric multi-layer film that are arrangedcrosswise therein and synthesize bundles of modulated rays of suchcolors, respectively. The bundles of rays synthesized therein passthrough a projection lens 3414 (namely, a projection means) and come toform images on a screen 3415.

The projection display 3400 configured in this way uses liquid crystallight valves, each of which is a light valve of the type that modulatespolarized light of a single kind. Thus, the projection display 3400 ofthis embodiment resolves substantial part of the problems of aconventional luminaire in that if randomly-polarized light is led to aliquid crystal light valve by using the conventional luminaire, half ofthe randomly-polarized light is absorbed by a polarizing plate and isconverted into heat and thus the efficiency in utilizing the light islow and in that a large cooling device which makes a great deal of noisefor controlling heat emitted from the polarizing plate is needed.

Namely, in the case of the projection display 3400 of this embodiment,the rotatory polarization is exerted only on one of the two kinds ofpolarized light, for instance, p-polarized light by the half-wave plate2904 in the polarization luminaire 3100 so that the plane ofpolarization thereof is made to extend in the same direction as in whichthe other kind of polarized light. Thus, the polarized lights, whosepolarization directions are uniform, are led to the first to thirdliquid crystal light valves 3403, 3405 and 3411. Consequently, theefficiency in utilizing the light can-be enhanced. Moreover, a brightprojected image can be obtained. Further, the quantity of light absorbedby the polarizing plate (not shown) can be reduced. Thereby, a rise intemperature of the polarizing plate can be suppressed. Consequently, itis realized that a cooling device can be made small and its noise can bereduced.

Furthermore, in the polarization luminaire 3100, the two kinds ofpolarized lights are separated in the transverse direction by the secondlens plate 2901 in accordance with the shape of the condenser lens 2911.Thus, the region to be illuminated, whose shape is a laterally elongatedrectangle, can be formed without wasting any quantity of light.Consequently, the polarization luminaire 3100 is suitable for alaterally-elongated liquid crystal light valve which can project animage which is easy to see and appeals strongly.

As stated in the description of the aforementioned Embodiment 22, thepolarization luminaire of this embodiment restrains the divergence of aflux of lights radiated from the polarization conversion prism array2903 in spite of the fact that the polarization conversion opticalelements are incorporated thereinto. This means that when illuminatingthe liquid crystal light valve, there is little light which is incidenton the liquid crystal light valve at a large angle of incidence.Therefore, a bright projected image can be realized even if anextremely-large-diameter projection lens having a small F-number is notused.

In addition, this embodiment uses a dichroic prism 3413 as the colorsynthesis means. Thus, the size of the device can be reduced. Moreover,the length of the optical path between the projection lens 3414 and eachof the liquid crystal light valves 3403, 3405 and 3411 is short. Thus,in the case of the device of this embodiment, a bright projected imagecan be realized even if a projection lens having a relatively smalldiameter is used. Further, in the case of this embodiment, the lightguiding means 3450 constituted by the relay lens system comprising theentrance side lens 3406, the relay lens 3408 and the exit side lens 3410is provided for blue rays. Consequently, irregularities in colors or thelike do not occur in projected images.

Incidentally, the projection display can be provided with an opticalsystem using mirrors which uses three dichroic mirrors as the colorsynthesis means. Needless to say, in such a case, the polarizationluminaire of this example can be incorporated into the projectiondisplay. Consequently, similarly as in the case of this example, abright high-quality projected image can be formed with good efficiencyin utilizing light.

Other Embodiments

Incidentally, in the case of most of the aforementioned embodiments, forexample, the p-polarized light is converted into the s-polarized lightin the polarized light conversion means. Needless to say, the uniformpolarization direction, which the polarized lights should have, may beeither of the two polarization directions of the s-polarized light andthe p-polarized light. Further, the planes of polarization of thepolarized lights may be made to extend in the same direction by exertingthe rotatory polarization on both of the p-polarized light and thes-polarized light through the retardation layers.

On the other hand, in the case of each of the aforementionedembodiments, it is assumed that the half-wave plate and the quarter-waveplate are retardation films made of ordinary high-polymer films. Theseretardation films, however, may be made of twisted nematic liquidcrystals (namely, TN liquid crystals). In the case of using TN liquidcrystals, the dependence on wavelength of the retardation film can belowered. Thus, in comparison with the case of using ordinaryhigh-polymer films, the polarization conversion performance of thehalf-wave plate and the quarter-wave plate can be enhanced.

INDUSTRIAL APPLICABILITY

A polarization luminaire of the present invention having a system of theoptical integrator is provided with polarized light splitting means forsplitting a light radiated from a light source into two kinds ofpolarized lights whose polarization directions are perpendicular to eachother and whose traveling directions are apart from each other by anangle of less than 90 degrees, and polarization conversion means forcausing the two kinds of polarized lights to have the same polarizationdirection. Moreover, this polarization luminaire of the presentinvention employs a configuration in which the polarized light splittingmeans is placed on one of an entrance side and an exit side of a firstlens plate of the system of the optical integrator, or is placed in asecond lens plate.

Thus, in the case of the polarization luminaire of the presentinvention, polarized lights, whose polarization directions are uniform,can be applied to a region to be illuminated. Therefore, in the case ofusing the polarization luminaire of the present invention in aprojection display which uses a liquid crystal light valve, polarizedlights, whose planes of polarization extend in the same direction, canbe supplied to the liquid crystal light valve. The efficiency inutilizing light is enhanced. Further, the brightness of a projectedimage can be enhanced. Moreover, the quantity of light absorbed by apolarizing plate is reduced, so that a rise in temperature of thepolarizing plate is suppressed. Consequently, it is realized a coolingdevice can be made small and its noise can be reduced.

Furthermore, in accordance with the present invention, the spatialdivergence of polarized lights due to the separation thereof is avoidedby utilizing a process of generating micro-secondary light sourceimages, which is a characteristic feature of the system of the opticalintegrator. Thus, the size of the luminaire of the present invention canbe prevented from exceeding the sizes of conventional luminaries.

Furthermore, in the case that a prism beam splitter is used as thepolarized light splitting means, the ability of a polarized lightsplitting portion to split polarized light is thermally stable, becausea thermally stable dielectric multi-layer film is used as the polarizedlight splitting film. The polarized light splitting portion, therefore,exerts the stable polarized light splitting ability at all times even inthe case of the projection display required to output a large quantityof light.

In the case of employing a configuration in which a prism bean splitteris placed on the entrance side of the first lens plate, the goodseparation characteristics for separating p-polarized light froms-polarized light can be obtained. This is because of the fact that thepolarized light separating characteristics of a prism beam splitterdepend on the angle of incidence of light and thus the polarized lightseparating characteristics thereof can be made to be more favorable andstable by causing rays, which have been made by a reflector to be nearlyparallel rays, to entered the prism beam splitter.

Further, the size of the luminaire can be further reduced by employing aconfiguration in which the prism beam splitter is placed on the exitside of the first lens plate, because the gap between the first lensplate and the second lens plate can be narrowed.

1. A polarization luminaire, comprising: a light source that emits light having random polarization directions; a first lens plate comprising a plurality of condenser lenses, the condenser lenses being decentered lenses; and a second lens plate that is a composite layered element comprising a condenser lens array; a polarization beam splitting prism array that splits each light emitted from both the plurality of condenser lenses and the condenser lens array into a p-polarized light and an s-polarized light; and a half-wave plate placed on an exit side of the polarization beam splitting prism array, wherein the polarization beam splitting prism array includes a plurality of polarizing beam splitters and a plurality of reflecting mirrors alternately arranged, the light source being placed by being shifted in parallel with respect to a system optical axis of the polarization luminaire.
 2. The polarization luminaire according to claim 1, further comprising an exit side lens disposed on the exit side of the polarization beam splitting prism array.
 3. The polarization luminaire according to claim 1, further comprising a condenser lens array disposed on the exit side of the polarization beam splitting prism array, the condenser lens array having a plurality of condenser lenses.
 4. The polarization luminaire according to claim 1, wherein a region to be illuminated by the luminaire has an oblong shape, and the polarization beam splitting prism array splits the light along a longitudinal direction of the region.
 5. A projector, comprising: a luminaire; modulation device that modulates a polarized light outputted from the luminaire; and a projection optical system that projects a modulated light, wherein the luminaire comprises: a light source that emits light having random polarization directions, a first lens plate comprising a plurality of condenser lenses, the condenser lenses being decentered lenses, and a second lens plate that is a composite layered element comprising a condenser lens array; a polarization beam splitting prism array that splits each light emitted from both the plurality of condenser lenses and the condenser lens array into a p-polarized light and an s-polarized light; and a half-wave plate placed on an exit side of the polarization beam splitting prism array, wherein the polarization beam splitting prism array includes a plurality of polarizing beam splitters and a plurality of reflecting mirrors alternately arranged, the second lens plate being placed by being shifted in parallel to a system optical axis of the luminaire.
 6. The projector according to claim 5, further comprising an exit side lens disposed on the exit side of the polarization beam splitting prism array.
 7. The projector according to claim 5, further comprising a condenser lens array disposed on the exit side of the polarization beam splitting prism array, the condenser lens array having a plurality of condenser lenses.
 8. The projector according to claim 5, wherein a region to be illuminated by the luminaire has an oblong shape, and the polarization beam splitting prism array splits the light along a longitudinal direction of the region. 